Convert date fields to iso string array handling

package.json

@@ -49,10 +49,11 @@
     "eslint-config-prettier": "^9.0.0",
     "eslint-plugin-import": "^2.29.0",
     "eslint-plugin-prettier": "^5.0.1",
-    "eslint-plugin-vitest": "^0.3.8",
+    "eslint-plugin-vitest": "^0.3.9",
     "prettier": "^3.0.3",
     "typescript": "^5.2.2",
     "vitest": "^0.34.6",
-    "zod": "^3.22.4"
+    "zod": "^3.22.4",
+    "vite": "4.5.0"
   }
 }

src/utils/objectUtils.spec.ts

@@ -1,4 +1,4 @@
-import { expect, expectTypeOf } from 'vitest'
+import { expect } from 'vitest'
 
 import {
   convertDateFieldsToIsoString,
@@ -542,7 +542,6 @@ describe('objectUtils', () => {
         code: 100,
         reason: 'reason',
       })
-      expectTypeOf(output).toMatchTypeOf<TestExpectedType>()
     })
 
     it('simple array', () => {
@@ -608,6 +607,45 @@ describe('objectUtils', () => {
       })
     })
 
+    it('properly handles all types of arrays', () => {
+      const date = new Date()
+      const input = {
+        array1: [date, date],
+        array2: [1, 2],
+        array3: ['a', 'b'],
+        array4: [
+          { id: 1, value: 'value', date, code: 100 } satisfies TestInputType,
+          { id: 2, value: 'value2', date, code: 200 } satisfies TestInputType,
+        ],
+        array5: [1, date, 'a', { id: 1, value: 'value', date, code: 100 } satisfies TestInputType],
+      }
+
+      type Expected = {
+        array1: string[]
+        array2: number[]
+        array3: string[]
+        array4: TestExpectedType[]
+        array5: (number | string | TestExpectedType)[]
+      }
+      const output: Expected = convertDateFieldsToIsoString(input)
+
+      expect(output).toStrictEqual({
+        array1: [date.toISOString(), date.toISOString()],
+        array2: [1, 2],
+        array3: ['a', 'b'],
+        array4: [
+          { id: 1, value: 'value', date: date.toISOString(), code: 100 },
+          { id: 2, value: 'value2', date: date.toISOString(), code: 200 },
+        ],
+        array5: [
+          1,
+          date.toISOString(),
+          'a',
+          { id: 1, value: 'value', date: date.toISOString(), code: 100 },
+        ],
+      })
+    })
+
     it('nested objects and array', () => {
       const date1 = new Date()
       const date2 = new Date()

src/utils/objectUtils.ts

@@ -139,20 +139,26 @@ export function convertDateFieldsToIsoString<Input extends object>(
   object: Input | Input[],
 ): ExactlyLikeWithDateAsString<Input> | ExactlyLikeWithDateAsString<Input>[] {
   if (Array.isArray(object)) {
-    return object.map((item) => convertDateFieldsToIsoString(item))
+    // @ts-ignore
+    return object.map(convertDateFieldsToIsoStringAux)
   }
 
   return Object.entries(object).reduce((result, [key, value]) => {
-    if (value instanceof Date) {
-      // @ts-ignore
-      result[key] = value.toISOString()
-    } else if (value && typeof value === 'object') {
-      // @ts-ignore
-      result[key] = convertDateFieldsToIsoString(value)
-    } else {
-      // @ts-ignore
-      result[key] = value
-    }
+    // @ts-ignore
+    result[key] = convertDateFieldsToIsoStringAux(value)
     return result
   }, {} as ExactlyLikeWithDateAsString<Input>)
 }
+
+function convertDateFieldsToIsoStringAux<T>(item: T): DatesAsString<T> {
+  if (item instanceof Date) {
+    // @ts-ignore
+    return item.toISOString()
+  } else if (item && typeof item === 'object') {
+    // @ts-ignore
+    return convertDateFieldsToIsoString(item)
+  } else {
+    // @ts-ignore
+    return item
+  }
+}