From 5c46c07e272d46ea7c95b7bf0cdd510a93e4c6d6 Mon Sep 17 00:00:00 2001
From: kazuya kawaguchi <kawakazu80@gmail.com>
Date: Wed, 8 Mar 2017 13:44:41 +0900
Subject: [PATCH] :star: new: add `sync` option

---
 decls/i18n.js               |  8 ++++++--
 src/index.js                | 23 +++++++++++++++++++++++
 src/mixin.js                | 10 +++++++++-
 test/unit/component.test.js | 23 ++++++++++++++++++++++-
 4 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/decls/i18n.js b/decls/i18n.js
index 6d1853df8..4a8b91014 100644
--- a/decls/i18n.js
+++ b/decls/i18n.js
@@ -11,12 +11,14 @@ declare type I18nOptions = {
   formatter?: Formatter,
   missing?: MissingHandler,
   root?: I18n,
-  fallbackRoot?: boolean
+  fallbackRoot?: boolean,
+  sync?: boolean
 }
 
 declare interface I18n {
   static install: () => void,
   static version: string,
+  get vm() :any,
   get locale (): string,
   set locale (locale: string): void,
   get fallbackLocale (): string,
@@ -29,7 +31,9 @@ declare interface I18n {
   set formatter (formatter: Formatter): void,
   t (key: string, ...args: any): string,
   tc (key: string, choice?: number, ...args: any): any,
-  te (key: string, ...args: any): boolean
+  te (key: string, ...args: any): boolean,
+  watchLocale (): any,
+  unwatchLocale (): boolean
 }
 
 declare type FormatterOptions = Dictionary<any>
diff --git a/src/index.js b/src/index.js
index 32916d2c4..6836a9bd8 100644
--- a/src/index.js
+++ b/src/index.js
@@ -14,10 +14,12 @@ export default class VueI18n {
   _vm: any
   _formatter: Formatter
   _root: ?I18n
+  _sync: ?boolean
   _fallbackRoot: boolean
   _fallbackLocale: string
   _missing: ?MissingHandler
   _exist: Function
+  _watcher: any
 
   constructor (options: I18nOptions = {}) {
     const locale: string = options.locale || 'en-US'
@@ -27,6 +29,7 @@ export default class VueI18n {
     this._formatter = options.formatter || new BaseFormatter()
     this._missing = options.missing
     this._root = options.root || null
+    this._sync = options.sync || false
     this._fallbackRoot = options.fallbackRoot || false
 
     this._exist = (message: Object, key: string): boolean => {
@@ -44,6 +47,26 @@ export default class VueI18n {
     Vue.config.silent = silent
   }
 
+  watchLocale (): any {
+    if (!this._sync || !this._root) { return null }
+    const target: any = this._vm
+    this._watcher = this._root.vm.$watch('locale', (val) => {
+      target.$set(target, 'locale', val)
+    }, { immediate: true })
+    return this._watcher
+  }
+
+  unwatchLocale (): boolean {
+    if (!this._sync || !this._watcher) { return false }
+    if (this._watcher) {
+      this._watcher()
+      delete this._watcher
+    }
+    return true
+  }
+
+  get vm (): any { return this._vm }
+
   get messages (): Messages { return this._vm.$data.messages }
   set messages (messages: Messages): void { this._vm.$set(this._vm, 'messages', messages) }
 
diff --git a/src/mixin.js b/src/mixin.js
index 94cfbb147..9c7d54583 100644
--- a/src/mixin.js
+++ b/src/mixin.js
@@ -53,9 +53,12 @@ export default {
           options.i18n.root = this.$root.$i18n
         }
         this.$i18n = new VueI18n(options.i18n)
+        if (options.i18n.sync) {
+          this._localeWatcher = this.$i18n.watchLocale()
+        }
       } else {
         if (process.env.NODE_ENV !== 'production') {
-          warn(`Cannot be interpreted 'i18n' options.`)
+          warn(`Cannot be interpreted 'i18n' option.`)
         }
       }
     } else if (this.$root && this.$root.$i18n && typeName(this.$root.$i18n) === 'VueI18n') {
@@ -65,6 +68,11 @@ export default {
   },
 
   destroyed () {
+    if (this._localeWatcher) {
+      this.$i18n.unwatchLocale()
+      delete this._localeWatcher
+    }
+
     this.$i18n = null
   }
 }
diff --git a/test/unit/component.test.js b/test/unit/component.test.js
index 8b4b7703b..83d67b506 100644
--- a/test/unit/component.test.js
+++ b/test/unit/component.test.js
@@ -46,9 +46,26 @@ describe('component translation', () => {
           }
         },
         child2: {
+          components: {
+            'sub-child2': {
+              i18n: {
+                sync: true,
+                messages: {
+                  en: { who: 'sub-child2' },
+                  ja: { who: 'サブの子2' }
+                }
+              },
+              render (h) {
+                return h('div', {}, [
+                  h('p', { ref: 'who' }, [this.$t('who')])
+                ])
+              }
+            }
+          },
           render (h) {
             return h('div', {}, [
-              h('p', { ref: 'who' }, [this.$t('who')])
+              h('p', { ref: 'who' }, [this.$t('who')]),
+              h('sub-child2', { ref: 'sub-child2' })
             ])
           }
         }
@@ -70,11 +87,13 @@ describe('component translation', () => {
     const child1Fallback = vm.$refs.child1.$refs.fallback
     const child2 = vm.$refs.child2.$refs.who
     const subChild1 = vm.$refs.child1.$refs['sub-child1'].$refs.who
+    const subChild2 = vm.$refs.child2.$refs['sub-child2'].$refs.who
     assert.equal(root.textContent, 'ルート')
     assert.equal(child1.textContent, 'child1')
     assert.equal(child1Fallback.textContent, 'フォールバック')
     assert.equal(child2.textContent, 'ルート')
     assert.equal(subChild1.textContent, 'ルート')
+    assert.equal(subChild2.textContent, 'サブの子2')
 
     // change locale
     i18n.locale = 'en'
@@ -85,6 +104,8 @@ describe('component translation', () => {
       assert.equal(child1Fallback.textContent, 'fallback')
       assert.equal(child2.textContent, 'root')
       assert.equal(subChild1.textContent, 'root')
+      assert.equal(subChild2.textContent, 'sub-child2')
+
       vm.$destroy()
     }).then(() => {
       assert(vm.$i18n === null)