From b9fc188ae64072983276cfbb6449f90014e85674 Mon Sep 17 00:00:00 2001
From: Andreas Fehn <fehnomenal@fehn.systems>
Date: Sun, 31 Dec 2023 11:52:29 +0100
Subject: [PATCH] Add array search params (#585)

* allow array search params

* make array search params more type safe

* join array values by default

* lint

* export appendSp

* extract string or undefined helper

* default to split mode

* expand array test routes

* changeset

* add array params to tests
---
 .changeset/afraid-hats-invent.md              |   5 +
 .../vite-plugin-kit-routes/src/lib/ROUTES.ts  |  65 ++++++++---
 .../vite-plugin-kit-routes/src/lib/format.ts  |  40 +++++--
 .../vite-plugin-kit-routes/src/lib/plugin.ts  |  89 +++++++++++----
 .../src/lib/plugins.spec.ts                   |  14 +++
 .../src/routes/+layout.svelte                 |   4 +-
 .../src/routes/spArray/+page.svelte           |  10 ++
 .../src/routes/spArrayComma/+page.svelte      |  10 ++
 .../src/test/ROUTES_base.ts                   |  54 ++++++---
 .../src/test/ROUTES_format-object-path.ts     |  64 +++++++----
 .../ROUTES_format-object-path_shortened.ts    |  62 +++++++---
 .../src/test/ROUTES_format-object-symbol.ts   |  70 ++++++++----
 .../ROUTES_format-object-symbol_shortened.ts  |  68 +++++++----
 .../ROUTES_format-route-and-object-path.ts    |  64 +++++++----
 ..._format-route-and-object-path_shortened.ts |  62 +++++++---
 .../ROUTES_format-route-and-object-symbol.ts  |  64 +++++++----
 ...ormat-route-and-object-symbol_shortened.ts |  62 +++++++---
 .../src/test/ROUTES_format-route-path.ts      |  64 +++++++----
 .../ROUTES_format-route-path_shortened.ts     |  62 +++++++---
 .../src/test/ROUTES_format-route-symbol.ts    |  64 +++++++----
 .../ROUTES_format-route-symbol_shortened.ts   |  62 +++++++---
 .../src/test/ROUTES_format-variables.ts       | 106 +++++++++++-------
 .../test/ROUTES_format-variables_shortened.ts | 106 +++++++++++-------
 .../src/test/ROUTES_post-update.ts            |  54 ++++++---
 .../vite-plugin-kit-routes/vite.config.ts     |   6 +
 25 files changed, 957 insertions(+), 374 deletions(-)
 create mode 100644 .changeset/afraid-hats-invent.md
 create mode 100644 packages/vite-plugin-kit-routes/src/routes/spArray/+page.svelte
 create mode 100644 packages/vite-plugin-kit-routes/src/routes/spArrayComma/+page.svelte

diff --git a/.changeset/afraid-hats-invent.md b/.changeset/afraid-hats-invent.md
new file mode 100644
index 00000000..b62e66e8
--- /dev/null
+++ b/.changeset/afraid-hats-invent.md
@@ -0,0 +1,5 @@
+---
+'vite-plugin-kit-routes': minor
+---
+
+support array search parameters
diff --git a/packages/vite-plugin-kit-routes/src/lib/ROUTES.ts b/packages/vite-plugin-kit-routes/src/lib/ROUTES.ts
index 8ea028ec..9a8d70b8 100644
--- a/packages/vite-plugin-kit-routes/src/lib/ROUTES.ts
+++ b/packages/vite-plugin-kit-routes/src/lib/ROUTES.ts
@@ -61,8 +61,8 @@ const PAGES = {
     params.lang = params.lang ?? 'fr'
     params.id = params.id ?? 'Vienna'
     return `${params?.lang ? `/${params?.lang}` : ''}/site/${params.id}${appendSp({
-      limit: params?.limit,
-      demo: params?.demo,
+      limit: params.limit,
+      demo: params.demo,
     })}`
   },
   '/site_contract/[siteId]-[contractId]': (params: {
@@ -73,7 +73,7 @@ const PAGES = {
   }) => {
     return `${params?.lang ? `/${params?.lang}` : ''}/site_contract/${params.siteId}-${
       params.contractId
-    }${appendSp({ limit: params?.limit })}`
+    }${appendSp({ limit: params.limit })}`
   },
   '/a/[...rest]/z': (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -84,6 +84,12 @@ const PAGES = {
   '/sp': (sp?: Record<string, string | number>) => {
     return `/sp${appendSp(sp)}`
   },
+  '/spArray': (params: { ids: number[] }) => {
+    return `/spArray${appendSp({ ids: params.ids })}`
+  },
+  '/spArrayComma': (params: { ids: number[] }) => {
+    return `/spArrayComma${appendSp({ ids: String(params.ids) })}`
+  },
 }
 
 /**
@@ -118,7 +124,7 @@ const ACTIONS = {
     limit?: number
   }) => {
     return `${params?.lang ? `/${params?.lang}` : ''}/contract/${params.id}${appendSp({
-      limit: params?.limit,
+      limit: params.limit,
     })}`
   },
   'create /site': (params?: {
@@ -154,7 +160,7 @@ const ACTIONS = {
     params.extra = params.extra ?? 'A'
     return `${params?.lang ? `/${params?.lang}` : ''}/site_contract/${params.siteId}-${
       params.contractId
-    }?/send${appendSp({ extra: params?.extra }, '&')}`
+    }?/send${appendSp({ extra: params.extra }, '&')}`
   },
 }
 
@@ -169,25 +175,41 @@ const LINKS = {
   gravatar: (params: { str: string; s?: number; d?: 'retro' | 'identicon' }) => {
     params.s = params.s ?? 75
     params.d = params.d ?? 'identicon'
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({
-      s: params?.s,
-      d: params?.d,
-    })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   },
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (
+  sp?: Record<string, ParamValue | ParamValue[]>,
+  prefix: '?' | '&' = '?',
+) => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -209,6 +231,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -275,6 +305,8 @@ export type KIT_ROUTES = {
     '/lay/root-layout': never
     '/lay/skip': never
     '/sp': never
+    '/spArray': never
+    '/spArrayComma': never
   }
   SERVERS: {
     'GET /server_func_get': never
@@ -304,6 +336,7 @@ export type KIT_ROUTES = {
     siteId: never
     contractId: never
     rest: never
+    ids: never
     locale: never
     redirectTo: never
     extra: never
diff --git a/packages/vite-plugin-kit-routes/src/lib/format.ts b/packages/vite-plugin-kit-routes/src/lib/format.ts
index 8d5d4db1..54cb4ee9 100644
--- a/packages/vite-plugin-kit-routes/src/lib/format.ts
+++ b/packages/vite-plugin-kit-routes/src/lib/format.ts
@@ -19,18 +19,34 @@ export const format = (margin: { left?: number; top?: number; bottom?: number },
   )
 }
 
-export const appendSp = `/**
+export const appendSp = `type ParamValue = string | number | undefined
+
+/**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return \`\${prefix}\${formated}\`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return \`\${prefix}\${formatted}\`
   }
   return ''
 }
@@ -50,6 +66,14 @@ export const currentSp = () => {
     record[key] = value
   }
   return record
+}
+
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
 }`
 
 export const routeFn = `// route function helpers
diff --git a/packages/vite-plugin-kit-routes/src/lib/plugin.ts b/packages/vite-plugin-kit-routes/src/lib/plugin.ts
index 9f1da81f..4127dc60 100644
--- a/packages/vite-plugin-kit-routes/src/lib/plugin.ts
+++ b/packages/vite-plugin-kit-routes/src/lib/plugin.ts
@@ -234,6 +234,14 @@ export type ExtendParam = {
 
 export type ExplicitSearchParam = ExtendParam & {
   required?: boolean
+  /**
+   * Controls how arrays are converted into parameters.
+   * `join` will join elements with `,` into a single parameter.
+   * With `split` the parameter will be repeated for each element.
+   *
+   * @default 'split'
+   */
+  arrayMode?: 'join' | 'split'
 }
 
 export const log = new Log('Kit Routes')
@@ -521,26 +529,50 @@ export function buildMetadata(
 
   const params = []
 
+  let isAllOptional = paramsFromPath.filter(c => !c.optional).length === 0
+  const paramsReq = paramsFromPath.filter(c => !c.optional)
+
   // custom search Param?
-  let explicit_search_params_to_function: string[] = []
+  const explicit_search_params_to_function: [param: string, val: string][] = []
   if (customConf.explicit_search_params) {
+    let someParamsHaveDefault = paramsFromPath.filter(c => c.default !== undefined).length > 0
+
     Object.entries(customConf.explicit_search_params).forEach(sp => {
-      paramsFromPath.push({
+      const param = {
         name: sp[0],
         optional: !sp[1].required,
         type: sp[1].type,
         default: sp[1].default,
         isArray: false,
-      })
-      explicit_search_params_to_function.push(
-        `${sp[0]}: params${sp[1].required ? '' : '?'}.${sp[0]}`,
-      )
+      }
+
+      paramsFromPath.push(param)
+
+      if (sp[1].required) {
+        isAllOptional = false
+        paramsReq.push(param)
+      }
+      if (sp[1].default !== undefined) {
+        someParamsHaveDefault = true
+      }
+    })
+
+    let paramsIsOptional = isAllOptional
+    if (options.format_short && paramsReq.length === 1) {
+      paramsIsOptional = true
+    }
+    if (someParamsHaveDefault) {
+      paramsIsOptional = false
+    }
+
+    Object.entries(customConf.explicit_search_params).forEach(sp => {
+      const val = `params${paramsIsOptional ? '?' : ''}.${sp[0]}`
+
+      explicit_search_params_to_function.push([sp[0], getSpValue(val, sp[1])])
     })
   }
 
-  let isAllOptional = paramsFromPath.filter(c => !c.optional).length === 0
   if (paramsFromPath.length > 0) {
-    const paramsReq = paramsFromPath.filter(c => !c.optional)
     if (options.format_short && paramsReq.length === 1) {
       // If only ONE required param, and we have only one, then let's put params optional
       isAllOptional = true
@@ -550,10 +582,11 @@ export function buildMetadata(
       // If it's in the explicite and it's THIS one, let's change the array...
       if (
         explicit_search_params_to_function.length === 1 &&
-        explicit_search_params_to_function[0] ===
-          `${paramsReq[0].name}: params${!paramsReq[0].optional ? '' : '?'}.${paramsReq[0].name}`
+        explicit_search_params_to_function[0][0] === paramsReq[0].name
       ) {
-        explicit_search_params_to_function = [paramsReq[0].name]
+        const sp = customConf.explicit_search_params![paramsReq[0].name]
+
+        explicit_search_params_to_function[0][1] = getSpValue(paramsReq[0].name, sp)
       } else {
         // in params
         toRet = toRet.replaceAll(`params.${paramsReq[0].name}`, paramsReq[0].name)
@@ -562,6 +595,10 @@ export function buildMetadata(
     params.push(`params${isAllOptional ? '?' : ''}: { ${formatArgs(paramsFromPath, options)} }`)
   }
 
+  const explicit_search_params = explicit_search_params_to_function
+    .map(([param, val]) => (param === val ? param : `${param}: ${val}`))
+    .join(', ')
+
   let fullSP = ''
   const wExtraSP =
     (customConf.extra_search_params === 'default' && useWithAppendSp) ||
@@ -574,11 +611,9 @@ export function buildMetadata(
   } else if (wExtraSP && customConf.explicit_search_params) {
     params.push(`sp?: Record<string, string | number>`)
     // We want explicite to be stronger and override sp
-    fullSP =
-      `\${appendSp({ ...sp, ${explicit_search_params_to_function.join(', ')}` +
-      ` }${appendSpPrefix})}`
+    fullSP = `\${appendSp({ ...sp, ${explicit_search_params} }${appendSpPrefix})}`
   } else if (!wExtraSP && customConf.explicit_search_params) {
-    fullSP = `\${appendSp({ ${explicit_search_params_to_function.join(', ')} }${appendSpPrefix})}`
+    fullSP = `\${appendSp({ ${explicit_search_params} }${appendSpPrefix})}`
   }
 
   let paramsDefaults = paramsFromPath
@@ -609,6 +644,18 @@ export function buildMetadata(
   return baseToReturn
 }
 
+function getSpValue(rawValue: string, param: ExplicitSearchParam) {
+  if (param.arrayMode === 'join') {
+    if (param.required || param.default !== undefined) {
+      return `String(${rawValue})`
+    }
+
+    return `StringOrUndefined(${rawValue})`
+  }
+
+  return rawValue
+}
+
 export function extractParamsFromPath(path: string, o: Options): Param[] {
   const options = getDefaultOption(o)
   const paramPattern = /\[+([^\]]+)]+/g
@@ -786,9 +833,9 @@ export const run = (atStart: boolean, o?: Options) => {
   if (allOk) {
     const result = write(options.generated_file_path, [
       `/* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */${options?.path_base ? `\nimport { base } from '$app/paths'` : ''}
 `,
@@ -804,7 +851,7 @@ ${c.files
       return (
         `export const ${c.type.slice(0, -1)}_${key.keyToUse} = (${key.strParams}) => {` +
         `${format({ bottom: 0, top: 1, left: 2 }, key.strDefault)}
-  return ${key.strReturn} 
+  return ${key.strReturn}
 }`
       )
     } else {
@@ -848,12 +895,12 @@ ${options?.format?.includes('object') ? `export ` : ``}` +
       // types
       `/**
 * Add this type as a generic of the vite plugin \`kitRoutes<KIT_ROUTES>\`.
-* 
+*
 * Full example:
 * \`\`\`ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -861,7 +908,7 @@ ${options?.format?.includes('object') ? `export ` : ``}` +
 * })
 * \`\`\`
 */
-export type KIT_ROUTES = { 
+export type KIT_ROUTES = {
 ${objTypes
   .map(c => {
     return `  ${c.type}${arrayToRecord(
diff --git a/packages/vite-plugin-kit-routes/src/lib/plugins.spec.ts b/packages/vite-plugin-kit-routes/src/lib/plugins.spec.ts
index cca33a51..9ef24545 100644
--- a/packages/vite-plugin-kit-routes/src/lib/plugins.spec.ts
+++ b/packages/vite-plugin-kit-routes/src/lib/plugins.spec.ts
@@ -349,6 +349,12 @@ describe('run()', async () => {
       site_contract_siteId_contractId: {
         explicit_search_params: { limit: { type: 'number' } },
       },
+      spArray: {
+        explicit_search_params: { ids: { type: 'number[]', required: true } },
+      },
+      spArrayComma: {
+        explicit_search_params: { ids: { type: 'number[]', required: true, arrayMode: 'join' } },
+      },
     },
     SERVERS: {},
     ACTIONS: {
@@ -824,6 +830,8 @@ describe('rmv Helper', () => {
         "lay/+layout.svelte",
         "page_server_woAction/+page.server.ts",
         "sp/+page.svelte",
+        "spArray/+page.svelte",
+        "spArrayComma/+page.svelte",
       ]
     `)
   })
@@ -870,6 +878,8 @@ describe('rmv Helper', () => {
         "lay/+layout.svelte",
         "page_server_woAction/+page.server.ts",
         "sp/+page.svelte",
+        "spArray/+page.svelte",
+        "spArrayComma/+page.svelte",
       ]
     `)
 
@@ -909,6 +919,8 @@ describe('rmv Helper', () => {
         "lay/+layout.svelte",
         "page_server_woAction/+page.server.ts",
         "sp/+page.svelte",
+        "spArray/+page.svelte",
+        "spArrayComma/+page.svelte",
       ]
     `)
   })
@@ -951,6 +963,8 @@ describe('rmv Helper', () => {
         "lay/+layout.svelte",
         "page_server_woAction/+page.server.ts",
         "sp/+page.svelte",
+        "spArray/+page.svelte",
+        "spArrayComma/+page.svelte",
       ]
     `)
   })
diff --git a/packages/vite-plugin-kit-routes/src/routes/+layout.svelte b/packages/vite-plugin-kit-routes/src/routes/+layout.svelte
index 3d1579c5..35e66727 100644
--- a/packages/vite-plugin-kit-routes/src/routes/+layout.svelte
+++ b/packages/vite-plugin-kit-routes/src/routes/+layout.svelte
@@ -82,7 +82,9 @@
     <a href={route('/lay/skip')}>Layout Skip</a>
   </li>
   <li>
-    <a href={route('/sp')}>Search Params</a>
+    <a href={route('/sp')}>Search Params</a> |
+    <a href={route('/spArray', { ids: [1, 2, 3] })}>Array Search Params</a> |
+    <a href={route('/spArrayComma', { ids: [1, 2, 3] })}>Array Search Params (comma-separated)</a>
   </li>
 </ul>
 
diff --git a/packages/vite-plugin-kit-routes/src/routes/spArray/+page.svelte b/packages/vite-plugin-kit-routes/src/routes/spArray/+page.svelte
new file mode 100644
index 00000000..1bdd4369
--- /dev/null
+++ b/packages/vite-plugin-kit-routes/src/routes/spArray/+page.svelte
@@ -0,0 +1,10 @@
+<script lang="ts">
+  import { page } from '$app/stores'
+
+  $: raw = $page.url.searchParams.getAll('ids')
+  $: parsed = raw.map(id => parseInt(id, 10))
+</script>
+
+<h2>Array Search Params</h2>
+
+<pre>{JSON.stringify({ raw, parsed }, null, 2)}</pre>
diff --git a/packages/vite-plugin-kit-routes/src/routes/spArrayComma/+page.svelte b/packages/vite-plugin-kit-routes/src/routes/spArrayComma/+page.svelte
new file mode 100644
index 00000000..4c468b5a
--- /dev/null
+++ b/packages/vite-plugin-kit-routes/src/routes/spArrayComma/+page.svelte
@@ -0,0 +1,10 @@
+<script lang="ts">
+  import { page } from '$app/stores'
+
+  $: raw = $page.url.searchParams.get('ids')
+  $: parsed = raw?.split(',').map(id => parseInt(id, 10))
+</script>
+
+<h2>Array Search Params (comma-separated)</h2>
+
+<pre>{JSON.stringify({ raw, parsed }, null, 2)}</pre>
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_base.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_base.ts
index 039335ff..4d121599 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_base.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_base.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 import { base } from '$app/paths'
@@ -50,7 +50,9 @@ const PAGES = {
   "/lay/normal": `${base}/lay/normal`,
   "/lay/root-layout": `${base}/lay/root-layout`,
   "/lay/skip": `${base}/lay/skip`,
-  "/sp": `${base}/sp`
+  "/sp": `${base}/sp`,
+  "/spArray": `${base}/spArray`,
+  "/spArrayComma": `${base}/spArrayComma`
 }
 
 /**
@@ -106,18 +108,34 @@ const LINKS = {
   
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -139,6 +157,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -168,12 +194,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -181,8 +207,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'id' | 'lang', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'id' | 'lang', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'id' | 'lang', 'create /site': 'lang', 'update /site/[id]': 'id' | 'lang', 'delete /site/[id]': 'id' | 'lang', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: Record<string, never>
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path.ts
index ed6588f0..309ec9ed 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -84,7 +86,7 @@ export const SERVERS = {
  */
 export const ACTIONS = {
   "default /contract/[id]": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create /site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +117,38 @@ export const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,14 +170,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -167,8 +193,8 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'id' | 'lang', 'create /site': 'lang', 'update /site/[id]': 'id' | 'lang', 'delete /site/[id]': 'id' | 'lang', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path_shortened.ts
index 543ce5ae..506ad881 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-path_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +118,38 @@ export const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,14 +171,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -168,8 +194,8 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'lang' | 'id', 'create /site': 'lang', 'update /site/[id]': 'lang' | 'id', 'delete /site/[id]': 'lang' | 'id', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol.ts
index 93bd9d37..91a73e25 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,13 @@ export const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": (params: { ids: (number[]) }) => {
+    return `/spArray${appendSp({ ids: params.ids })}`
+  },
+  "spArrayComma": (params: { ids: (number[]) }) => {
+    return `/spArrayComma${appendSp({ ids: String(params.ids) })}`
+  }
 }
 
 /**
@@ -84,7 +90,7 @@ export const SERVERS = {
  */
 export const ACTIONS = {
   "default_contract_id": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create_site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +106,7 @@ export const ACTIONS = {
   },
   "send_site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +121,38 @@ export const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,14 +174,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -167,10 +197,10 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET_server_func_get': never, 'POST_server_func_post': never, 'GET_contract': 'lang', 'POST_contract': 'lang', 'GET_site': 'lang', 'GET_api_graphql': never, 'POST_api_graphql': never, 'GET_data_errors_locale_json': 'locale' }
   ACTIONS: { 'default_contract_id': 'id' | 'lang', 'create_site': 'lang', 'update_site_id': 'id' | 'lang', 'delete_site_id': 'id' | 'lang', 'noSatisfies_site_contract': 'lang', 'send_site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
-  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
+  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, ids: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
 }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol_shortened.ts
index c3b80c1c..ef001da3 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-object-symbol_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,13 @@ export const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": (ids: (number[]), params?: {  }) => {
+    return `/spArray${appendSp({ ids })}`
+  },
+  "spArrayComma": (ids: (number[]), params?: {  }) => {
+    return `/spArrayComma${appendSp({ ids: String(ids) })}`
+  }
 }
 
 /**
@@ -100,7 +106,7 @@ export const ACTIONS = {
   },
   "send_site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +122,38 @@ export const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,14 +175,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -168,10 +198,10 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET_server_func_get': never, 'POST_server_func_post': never, 'GET_contract': 'lang', 'POST_contract': 'lang', 'GET_site': 'lang', 'GET_api_graphql': never, 'POST_api_graphql': never, 'GET_data_errors_locale_json': 'locale' }
   ACTIONS: { 'default_contract_id': 'lang' | 'id', 'create_site': 'lang', 'update_site_id': 'lang' | 'id', 'delete_site_id': 'lang' | 'id', 'noSatisfies_site_contract': 'lang', 'send_site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
-  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
+  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, ids: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
 }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path.ts
index 412598de..a05b5b56 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -84,7 +86,7 @@ export const SERVERS = {
  */
 export const ACTIONS = {
   "default /contract/[id]": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create /site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +117,38 @@ export const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,6 +170,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -181,12 +207,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -194,8 +220,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'id' | 'lang', 'create /site': 'lang', 'update /site/[id]': 'id' | 'lang', 'delete /site/[id]': 'id' | 'lang', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path_shortened.ts
index 8e937489..4d84f4e1 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-path_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +118,38 @@ export const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,6 +171,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -182,12 +208,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -195,8 +221,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'lang' | 'id', 'create /site': 'lang', 'update /site/[id]': 'lang' | 'id', 'delete /site/[id]': 'lang' | 'id', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol.ts
index b03bbe9d..c84f08e0 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": `/spArray`,
+  "spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -84,7 +86,7 @@ export const SERVERS = {
  */
 export const ACTIONS = {
   "default contract_id": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +117,38 @@ export const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,6 +170,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -181,12 +207,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -194,8 +220,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET server_func_get': never, 'POST server_func_post': never, 'GET contract': 'lang', 'POST contract': 'lang', 'GET site': 'lang', 'GET api_graphql': never, 'POST api_graphql': never, 'GET data_errors_locale_json': 'locale' }
   ACTIONS: { 'default contract_id': 'id' | 'lang', 'create site': 'lang', 'update site_id': 'id' | 'lang', 'delete site_id': 'id' | 'lang', 'noSatisfies site_contract': 'lang', 'send site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol_shortened.ts
index 7b5c8e54..b3709397 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-and-object-symbol_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ export const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,9 @@ export const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": `/spArray`,
+  "spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -100,7 +102,7 @@ export const ACTIONS = {
   },
   "send site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +118,38 @@ export const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,6 +171,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -182,12 +208,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -195,8 +221,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET server_func_get': never, 'POST server_func_post': never, 'GET contract': 'lang', 'POST contract': 'lang', 'GET site': 'lang', 'GET api_graphql': never, 'POST api_graphql': never, 'GET data_errors_locale_json': 'locale' }
   ACTIONS: { 'default contract_id': 'lang' | 'id', 'create site': 'lang', 'update site_id': 'lang' | 'id', 'delete site_id': 'lang' | 'id', 'noSatisfies site_contract': 'lang', 'send site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path.ts
index 71ee9f44..ff5bb71f 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,9 @@ const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -84,7 +86,7 @@ const SERVERS = {
  */
 const ACTIONS = {
   "default /contract/[id]": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create /site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +102,7 @@ const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +117,38 @@ const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,6 +170,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -181,12 +207,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -194,8 +220,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'id' | 'lang', 'create /site': 'lang', 'update /site/[id]': 'id' | 'lang', 'delete /site/[id]': 'id' | 'lang', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path_shortened.ts
index 1e1cedc4..da28aba7 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-path_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "/site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "/a/[...rest]/z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,9 @@ const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -100,7 +102,7 @@ const ACTIONS = {
   },
   "send /site_contract/[siteId]-[contractId]": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +118,38 @@ const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,6 +171,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -182,12 +208,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -195,8 +221,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'lang' | 'id', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'lang' | 'id', '/match/[id=int]': 'lang' | 'id', '/site': 'lang', '/site/[id]': 'lang' | 'id', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'lang' | 'id', 'create /site': 'lang', 'update /site/[id]': 'lang' | 'id', 'delete /site/[id]': 'lang' | 'id', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol.ts
index b7660fc7..c006b204 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (params: { rest: (string | number)[] }) => {
     return `/a/${params.rest?.join('/')}/z`
@@ -54,7 +54,9 @@ const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": `/spArray`,
+  "spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -84,7 +86,7 @@ const SERVERS = {
  */
 const ACTIONS = {
   "default contract_id": (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
   },
   "create site": (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
     return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
@@ -100,7 +102,7 @@ const ACTIONS = {
   },
   "send site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -115,22 +117,38 @@ const LINKS = {
   "gravatar": (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -152,6 +170,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -181,12 +207,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -194,8 +220,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET server_func_get': never, 'POST server_func_post': never, 'GET contract': 'lang', 'POST contract': 'lang', 'GET site': 'lang', 'GET api_graphql': never, 'POST api_graphql': never, 'GET data_errors_locale_json': 'locale' }
   ACTIONS: { 'default contract_id': 'id' | 'lang', 'create site': 'lang', 'update site_id': 'id' | 'lang', 'delete site_id': 'id' | 'lang', 'noSatisfies site_contract': 'lang', 'send site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol_shortened.ts
index 8edea596..250c0f51 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-route-symbol_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -43,10 +43,10 @@ const PAGES = {
     params = params ?? {}
     params.lang = params.lang ?? "fr"; 
     params.id = params.id ?? "Vienna"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
   },
   "site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
   },
   "a_rest_z": (rest: (string | number)[], params?: {  }) => {
     return `/a/${rest?.join('/')}/z`
@@ -54,7 +54,9 @@ const PAGES = {
   "lay_normal": `/lay/normal`,
   "lay_root_layout": `/lay/root-layout`,
   "lay_skip": `/lay/skip`,
-  "sp": `/sp`
+  "sp": `/sp`,
+  "spArray": `/spArray`,
+  "spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -100,7 +102,7 @@ const ACTIONS = {
   },
   "send site_contract_siteId_contractId": (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
     params.extra = params.extra ?? "A"; 
-    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}`
+    return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
   }
 }
 
@@ -116,22 +118,38 @@ const LINKS = {
     params = params ?? {}
     params.s = params.s ?? 75; 
     params.d = params.d ?? "identicon"; 
-    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}`
+    return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
   }
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -153,6 +171,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -182,12 +208,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -195,8 +221,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET server_func_get': never, 'POST server_func_post': never, 'GET contract': 'lang', 'POST contract': 'lang', 'GET site': 'lang', 'GET api_graphql': never, 'POST api_graphql': never, 'GET data_errors_locale_json': 'locale' }
   ACTIONS: { 'default contract_id': 'lang' | 'id', 'create site': 'lang', 'update site_id': 'lang' | 'id', 'delete site_id': 'lang' | 'id', 'noSatisfies site_contract': 'lang', 'send site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables.ts
index cfbd831d..478d8cdb 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -12,48 +12,54 @@ export const PAGE__ROOT = `/`
 export const PAGE_subGroup = `/subGroup`
 export const PAGE_subGroup_user = `/subGroup/user`
 export const PAGE_subGroup2 = (params: { first: (string | number) }) => {
-  return `/subGroup2${appendSp({ first: params.first })}` 
+  return `/subGroup2${appendSp({ first: params.first })}`
 }
 export const PAGE_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }, sp?: Record<string, string | number>) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract${appendSp(sp)}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract${appendSp(sp)}`
 }
 export const PAGE_contract_id = (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}`
 }
 export const PAGE_gp_one = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/gp/one` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/gp/one`
 }
 export const PAGE_gp_two = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/gp/two` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/gp/two`
 }
 export const PAGE_main = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/main` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/main`
 }
 export const PAGE_match_id_ab = (params: { id: (Parameters<typeof import('../params/ab.ts').match>[0]), lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/match/${params.id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/match/${params.id}`
 }
 export const PAGE_match_id_int = (params: { id: (number), lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/match/${params.id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/match/${params.id}`
 }
 export const PAGE_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }, sp?: Record<string, string | number>) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site${appendSp({ ...sp, limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site${appendSp({ ...sp, limit: params?.limit })}`
 }
 export const PAGE_site_id = (params?: { lang?: ('fr' | 'hu' | undefined), id?: (string), limit?: (number), demo?: (string) }) => {
   params = params ?? {}
   params.lang = params.lang ?? "fr"; 
   params.id = params.id ?? "Vienna"; 
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
 }
 export const PAGE_site_contract_siteId_contractId = (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
 }
 export const PAGE_a_rest_z = (params: { rest: (string | number)[] }) => {
-  return `/a/${params.rest?.join('/')}/z` 
+  return `/a/${params.rest?.join('/')}/z`
 }
 export const PAGE_lay_normal = `/lay/normal`
 export const PAGE_lay_root_layout = `/lay/root-layout`
 export const PAGE_lay_skip = `/lay/skip`
 export const PAGE_sp = `/sp`
+export const PAGE_spArray = (params: { ids: (number[]) }) => {
+  return `/spArray${appendSp({ ids: params.ids })}`
+}
+export const PAGE_spArrayComma = (params: { ids: (number[]) }) => {
+  return `/spArrayComma${appendSp({ ids: String(params.ids) })}`
+}
 
 /**
  * SERVERS
@@ -61,41 +67,41 @@ export const PAGE_sp = `/sp`
 export const SERVER_GET_server_func_get = `/server_func_get`
 export const SERVER_POST_server_func_post = `/server_func_post`
 export const SERVER_GET_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract`
 }
 export const SERVER_POST_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract`
 }
 export const SERVER_GET_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site`
 }
 export const SERVER_GET_api_graphql = `/api/graphql`
 export const SERVER_POST_api_graphql = `/api/graphql`
 export const SERVER_GET_data_errors_locale_json = (params: { locale: (string | number) }) => {
-  return `/data/errors/${params.locale}.json` 
+  return `/data/errors/${params.locale}.json`
 }
 
 /**
  * ACTIONS
  */
 export const ACTION_default_contract_id = (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${params.id}${appendSp({ limit: params.limit })}`
 }
 export const ACTION_create_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site?/create` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
 }
 export const ACTION_update_site_id = (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}?/update` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}?/update`
 }
 export const ACTION_delete_site_id = (params: { id: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}?/delete` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}?/delete`
 }
 export const ACTION_noSatisfies_site_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract?/noSatisfies` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract?/noSatisfies`
 }
 export const ACTION_send_site_contract_siteId_contractId = (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
   params.extra = params.extra ?? "A"; 
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
 }
 
 /**
@@ -103,26 +109,42 @@ export const ACTION_send_site_contract_siteId_contractId = (params: { siteId: (s
  */
 export const LINK_twitter = `https://twitter.com/jycouet`
 export const LINK_twitter_post = (params: { name: (string | number), id: (string | number) }) => {
-  return `https://twitter.com/${params.name}/status/${params.id}` 
+  return `https://twitter.com/${params.name}/status/${params.id}`
 }
 export const LINK_gravatar = (params: { str: (string | number), s?: (number), d?: ("retro" | "identicon") }) => {
   params.s = params.s ?? 75; 
   params.d = params.d ?? "identicon"; 
-  return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params?.s, d: params?.d })}` 
+  return `https://www.gravatar.com/avatar/${params.str}${appendSp({ s: params.s, d: params.d })}`
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -144,14 +166,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -159,10 +189,10 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'id' | 'lang', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'id' | 'lang', 'match_id_int': 'id' | 'lang', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET_server_func_get': never, 'POST_server_func_post': never, 'GET_contract': 'lang', 'POST_contract': 'lang', 'GET_site': 'lang', 'GET_api_graphql': never, 'POST_api_graphql': never, 'GET_data_errors_locale_json': 'locale' }
   ACTIONS: { 'default_contract_id': 'id' | 'lang', 'create_site': 'lang', 'update_site_id': 'id' | 'lang', 'delete_site_id': 'id' | 'lang', 'noSatisfies_site_contract': 'lang', 'send_site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
-  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
+  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, ids: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
 }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables_shortened.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables_shortened.ts
index 3993886b..1b0bbc3a 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables_shortened.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_format-variables_shortened.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -12,48 +12,54 @@ export const PAGE__ROOT = `/`
 export const PAGE_subGroup = `/subGroup`
 export const PAGE_subGroup_user = `/subGroup/user`
 export const PAGE_subGroup2 = (first: (string | number), params?: {  }) => {
-  return `/subGroup2${appendSp({ first })}` 
+  return `/subGroup2${appendSp({ first })}`
 }
 export const PAGE_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }, sp?: Record<string, string | number>) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract${appendSp(sp)}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract${appendSp(sp)}`
 }
 export const PAGE_contract_id = (id: (string | number), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${id}`
 }
 export const PAGE_gp_one = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/gp/one` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/gp/one`
 }
 export const PAGE_gp_two = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/gp/two` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/gp/two`
 }
 export const PAGE_main = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/main` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/main`
 }
 export const PAGE_match_id_ab = (id: (Parameters<typeof import('../params/ab.ts').match>[0]), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/match/${id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/match/${id}`
 }
 export const PAGE_match_id_int = (id: (number), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/match/${id}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/match/${id}`
 }
 export const PAGE_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }, sp?: Record<string, string | number>) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site${appendSp({ ...sp, limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site${appendSp({ ...sp, limit: params?.limit })}`
 }
 export const PAGE_site_id = (params?: { lang?: ('fr' | 'hu' | undefined), id?: (string), limit?: (number), demo?: (string) }) => {
   params = params ?? {}
   params.lang = params.lang ?? "fr"; 
   params.id = params.id ?? "Vienna"; 
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params?.limit, demo: params?.demo })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${params.id}${appendSp({ limit: params.limit, demo: params.demo })}`
 }
 export const PAGE_site_contract_siteId_contractId = (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}${appendSp({ limit: params.limit })}`
 }
 export const PAGE_a_rest_z = (rest: (string | number)[], params?: {  }) => {
-  return `/a/${rest?.join('/')}/z` 
+  return `/a/${rest?.join('/')}/z`
 }
 export const PAGE_lay_normal = `/lay/normal`
 export const PAGE_lay_root_layout = `/lay/root-layout`
 export const PAGE_lay_skip = `/lay/skip`
 export const PAGE_sp = `/sp`
+export const PAGE_spArray = (ids: (number[]), params?: {  }) => {
+  return `/spArray${appendSp({ ids })}`
+}
+export const PAGE_spArrayComma = (ids: (number[]), params?: {  }) => {
+  return `/spArrayComma${appendSp({ ids: String(ids) })}`
+}
 
 /**
  * SERVERS
@@ -61,41 +67,41 @@ export const PAGE_sp = `/sp`
 export const SERVER_GET_server_func_get = `/server_func_get`
 export const SERVER_POST_server_func_post = `/server_func_post`
 export const SERVER_GET_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract`
 }
 export const SERVER_POST_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract`
 }
 export const SERVER_GET_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site`
 }
 export const SERVER_GET_api_graphql = `/api/graphql`
 export const SERVER_POST_api_graphql = `/api/graphql`
 export const SERVER_GET_data_errors_locale_json = (locale: (string | number), params?: {  }) => {
-  return `/data/errors/${locale}.json` 
+  return `/data/errors/${locale}.json`
 }
 
 /**
  * ACTIONS
  */
 export const ACTION_default_contract_id = (id: (string | number), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string), limit?: (number) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${id}${appendSp({ limit: params?.limit })}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/contract/${id}${appendSp({ limit: params?.limit })}`
 }
 export const ACTION_create_site = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site?/create` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site?/create`
 }
 export const ACTION_update_site_id = (id: (string | number), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${id}?/update` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${id}?/update`
 }
 export const ACTION_delete_site_id = (id: (string | number), params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site/${id}?/delete` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site/${id}?/delete`
 }
 export const ACTION_noSatisfies_site_contract = (params?: { lang?: ('fr' | 'en' | 'hu' | 'at' | string) }) => {
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract?/noSatisfies` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract?/noSatisfies`
 }
 export const ACTION_send_site_contract_siteId_contractId = (params: { siteId: (string | number), contractId: (string | number), lang?: ('fr' | 'en' | 'hu' | 'at' | string), extra?: ('A' | 'B') }) => {
   params.extra = params.extra ?? "A"; 
-  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params?.extra }, '&')}` 
+  return `${params?.lang ? `/${params?.lang}`: ''}/site_contract/${params.siteId}-${params.contractId}?/send${appendSp({ extra: params.extra }, '&')}`
 }
 
 /**
@@ -103,27 +109,43 @@ export const ACTION_send_site_contract_siteId_contractId = (params: { siteId: (s
  */
 export const LINK_twitter = `https://twitter.com/jycouet`
 export const LINK_twitter_post = (params: { name: (string | number), id: (string | number) }) => {
-  return `https://twitter.com/${params.name}/status/${params.id}` 
+  return `https://twitter.com/${params.name}/status/${params.id}`
 }
 export const LINK_gravatar = (str: (string | number), params?: { s?: (number), d?: ("retro" | "identicon") }) => {
   params = params ?? {}
   params.s = params.s ?? 75; 
   params.d = params.d ?? "identicon"; 
-  return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params?.s, d: params?.d })}` 
+  return `https://www.gravatar.com/avatar/${str}${appendSp({ s: params.s, d: params.d })}`
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -145,14 +167,22 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -160,10 +190,10 @@ export const currentSp = () => {
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '_ROOT': never, 'subGroup': never, 'subGroup_user': never, 'subGroup2': never, 'contract': 'lang', 'contract_id': 'lang' | 'id', 'gp_one': 'lang', 'gp_two': 'lang', 'main': 'lang', 'match_id_ab': 'lang' | 'id', 'match_id_int': 'lang' | 'id', 'site': 'lang', 'site_id': 'lang' | 'id', 'site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang', 'a_rest_z': 'rest', 'lay_normal': never, 'lay_root_layout': never, 'lay_skip': never, 'sp': never, 'spArray': never, 'spArrayComma': never }
   SERVERS: { 'GET_server_func_get': never, 'POST_server_func_post': never, 'GET_contract': 'lang', 'POST_contract': 'lang', 'GET_site': 'lang', 'GET_api_graphql': never, 'POST_api_graphql': never, 'GET_data_errors_locale_json': 'locale' }
   ACTIONS: { 'default_contract_id': 'lang' | 'id', 'create_site': 'lang', 'update_site_id': 'lang' | 'id', 'delete_site_id': 'lang' | 'id', 'noSatisfies_site_contract': 'lang', 'send_site_contract_siteId_contractId': 'siteId' | 'contractId' | 'lang' }
   LINKS: { 'twitter': never, 'twitter_post': 'name' | 'id', 'gravatar': 'str' }
-  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
+  Params: { first: never, lang: never, id: never, limit: never, demo: never, siteId: never, contractId: never, rest: never, ids: never, locale: never, extra: never, name: never, str: never, s: never, d: never }
 }
diff --git a/packages/vite-plugin-kit-routes/src/test/ROUTES_post-update.ts b/packages/vite-plugin-kit-routes/src/test/ROUTES_post-update.ts
index eac6b94e..10ee8f96 100644
--- a/packages/vite-plugin-kit-routes/src/test/ROUTES_post-update.ts
+++ b/packages/vite-plugin-kit-routes/src/test/ROUTES_post-update.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
-/** 
+/**
  * This file was generated by 'vite-plugin-kit-routes'
- * 
+ *
  *      >> DO NOT EDIT THIS FILE MANUALLY <<
  */
 
@@ -49,7 +49,9 @@ const PAGES = {
   "/lay/normal": `/lay/normal`,
   "/lay/root-layout": `/lay/root-layout`,
   "/lay/skip": `/lay/skip`,
-  "/sp": `/sp`
+  "/sp": `/sp`,
+  "/spArray": `/spArray`,
+  "/spArrayComma": `/spArrayComma`
 }
 
 /**
@@ -105,18 +107,34 @@ const LINKS = {
   
 }
 
+type ParamValue = string | number | undefined
+
 /**
  * Append search params to a string
  */
-const appendSp = (sp?: Record<string, string | number | undefined>, prefix: '?' | '&' = '?') => {
+export const appendSp = (sp?: Record<string, ParamValue | ParamValue[]>, prefix: '?' | '&' = '?') => {
   if (sp === undefined) return ''
-  const mapping = Object.entries(sp)
-    .filter(c => c[1] !== undefined)
-    .map(c => [c[0], String(c[1])])
 
-  const formated = new URLSearchParams(mapping).toString()
-  if (formated) {
-    return `${prefix}${formated}`
+  const params = new URLSearchParams()
+  const append = (n: string, v: ParamValue) => {
+    if (v !== undefined) {
+      params.append(n, String(v))
+    }
+  }
+
+  for (const [name, val] of Object.entries(sp)) {
+    if (Array.isArray(val)) {
+      for (const v of val) {
+        append(name, v)
+      }
+    } else {
+      append(name, val)
+    }
+  }
+
+  const formatted = params.toString()
+  if (formatted) {
+    return `${prefix}${formatted}`
   }
   return ''
 }
@@ -138,6 +156,14 @@ export const currentSp = () => {
   return record
 }
 
+function StringOrUndefined(val: any) {
+  if (val === undefined) {
+    return undefined
+  }
+
+  return String(val)
+}
+
 // route function helpers
 type NonFunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]
 type FunctionKeys<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]
@@ -167,12 +193,12 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 
 /**
 * Add this type as a generic of the vite plugin `kitRoutes<KIT_ROUTES>`.
-* 
+*
 * Full example:
 * ```ts
 * import type { KIT_ROUTES } from '$lib/ROUTES'
 * import { kitRoutes } from 'vite-plugin-kit-routes'
-* 
+*
 * kitRoutes<KIT_ROUTES>({
 *  PAGES: {
 *    // here, key of object will be typed!
@@ -180,8 +206,8 @@ export function route<T extends keyof AllTypes>(key: T, ...params: any[]): strin
 * })
 * ```
 */
-export type KIT_ROUTES = { 
-  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'id' | 'lang', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never }
+export type KIT_ROUTES = {
+  PAGES: { '/': never, '/subGroup': never, '/subGroup/user': never, '/subGroup2': never, '/contract': 'lang', '/contract/[id]': 'id' | 'lang', '/gp/one': 'lang', '/gp/two': 'lang', '/main': 'lang', '/match/[id=ab]': 'id' | 'lang', '/match/[id=int]': 'id' | 'lang', '/site': 'lang', '/site/[id]': 'id' | 'lang', '/site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang', '/a/[...rest]/z': 'rest', '/lay/normal': never, '/lay/root-layout': never, '/lay/skip': never, '/sp': never, '/spArray': never, '/spArrayComma': never }
   SERVERS: { 'GET /server_func_get': never, 'POST /server_func_post': never, 'GET /contract': 'lang', 'POST /contract': 'lang', 'GET /site': 'lang', 'GET /api/graphql': never, 'POST /api/graphql': never, 'GET /data/errors/[locale].json': 'locale' }
   ACTIONS: { 'default /contract/[id]': 'id' | 'lang', 'create /site': 'lang', 'update /site/[id]': 'id' | 'lang', 'delete /site/[id]': 'id' | 'lang', 'noSatisfies /site_contract': 'lang', 'send /site_contract/[siteId]-[contractId]': 'siteId' | 'contractId' | 'lang' }
   LINKS: Record<string, never>
diff --git a/packages/vite-plugin-kit-routes/vite.config.ts b/packages/vite-plugin-kit-routes/vite.config.ts
index 93094259..45c7ea64 100644
--- a/packages/vite-plugin-kit-routes/vite.config.ts
+++ b/packages/vite-plugin-kit-routes/vite.config.ts
@@ -59,6 +59,12 @@ export default defineConfig({
         '/site_contract/[siteId]-[contractId]': {
           explicit_search_params: { limit: { type: 'number' } },
         },
+        '/spArray': {
+          explicit_search_params: { ids: { type: 'number[]', required: true } },
+        },
+        '/spArrayComma': {
+          explicit_search_params: { ids: { type: 'number[]', required: true, arrayMode: 'join' } },
+        },
       },
       SERVERS: {
         // site: {