From b9437ead90b80392c86fa15a8fbe1e0bc5fe351c Mon Sep 17 00:00:00 2001
From: Alexey <a.raiondesu@gmail.com>
Date: Fri, 21 Dec 2018 20:11:43 +0300
Subject: [PATCH] :zap: improvement(format): Add the path as argument to the
 custom formatter (#489) by @Raiondesu
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* ⚡improvement(types): typed autocomplete in date and number format options

Replace Number and Date format options with standard TS `Intl` types, while also adding guiding TS autocomplete to them.

This change exterminates the confusion of which types to follow, while preserving backwards-compatibility for types and adding optional autocomplete.

* ⚡improvement(types/test): add type constraints to format options

It's useful to check static variables types whenever possible.

* ⚡new(formatter): add path to the formatter arguments
and allow optional formatting

* ⚡improvement(types): backward-compatibility for #484

* 📃docs(formatter): add case for the undefined return type

* ⚡improvement(types): include the possible undefined return type

* ✅tests(issues): make formatter return undefined in test for #484

* update(formatter): change default foramtter invocation
from undefined to null
---
 decls/i18n.js            |  2 +-
 gitbook/en/formatting.md |  7 ++++++-
 src/index.js             | 18 +++++++++++++-----
 test/unit/issues.test.js | 28 ++++++++++++++++++++++++++++
 types/index.d.ts         |  2 +-
 5 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/decls/i18n.js b/decls/i18n.js
index e45e4ba1e..83d3193c2 100644
--- a/decls/i18n.js
+++ b/decls/i18n.js
@@ -110,5 +110,5 @@ declare interface I18n {
 };
 
 declare interface Formatter {
-  interpolate (message: string, values?: any): Array<any>
+  interpolate (message: string, values: any, path: string): (Array<any> | null)
 };
diff --git a/gitbook/en/formatting.md b/gitbook/en/formatting.md
index 5e4f35216..9dd989dd2 100644
--- a/gitbook/en/formatting.md
+++ b/gitbook/en/formatting.md
@@ -157,12 +157,17 @@ class CustomFormatter {
  //     -> passed values: Array (included VNode):
  //        `[VNode{ tag: 'p', text: 'kazupon', ...}, VNode{ tag: 'p', text: 'how are you?', ...}]`
  //
+ // @param {string} path
+ //   a path to the message, as passed into the $t/t() functions.
+ //   - $t('hello.louis') -> path === 'hello.louis'
+ //
  // @return {Array<any>}
  //   interpolated values. you need to return the following:
  //   - array of string, when is using `$t` or `$tc`.
  //   - array included VNode object, when is using `i18n` functional component.
+ //   - null - if you want the default vue-i18n formatter to handle the case
  //
- interpolate (message, values) {
+ interpolate (message, values, path) {
    // implement interpolation logic here
    // ...
 
diff --git a/src/index.js b/src/index.js
index 505da80de..ce7492587 100644
--- a/src/index.js
+++ b/src/index.js
@@ -37,6 +37,8 @@ const formatters = {
   'lower': (str) => str.toLocaleLowerCase()
 }
 
+const defaultFormatter = new BaseFormatter()
+
 export default class VueI18n {
   static install: () => void
   static version: string
@@ -76,7 +78,7 @@ export default class VueI18n {
     const numberFormats = options.numberFormats || {}
 
     this._vm = null
-    this._formatter = options.formatter || new BaseFormatter()
+    this._formatter = options.formatter || defaultFormatter
     this._missing = options.missing || null
     this._root = options.root || null
     this._sync = options.sync === undefined ? true : !!options.sync
@@ -246,7 +248,7 @@ export default class VueI18n {
       ret = this._link(locale, message, ret, host, interpolateMode, values, visitedLinkStack)
     }
 
-    return this._render(ret, interpolateMode, values)
+    return this._render(ret, interpolateMode, values, key)
   }
 
   _link (
@@ -322,9 +324,15 @@ export default class VueI18n {
     return ret
   }
 
-  _render (message: string, interpolateMode: string, values: any): any {
-    const ret = this._formatter.interpolate(message, values)
-    // if interpolateMode is **not** 'string' ('raw'),
+  _render (message: string, interpolateMode: string, values: any, path: string): any {
+    let ret = this._formatter.interpolate(message, values, path)
+
+    // If the custom formatter refuses to work - apply the default one
+    if (!ret) {
+      ret = defaultFormatter.interpolate(message, values, path)
+    }
+
+    // if interpolateMode is **not** 'string' ('row'),
     // return the compiled data (e.g. ['foo', VNode, 'bar']) with formatter
     return interpolateMode === 'string' ? ret.join('') : ret
   }
diff --git a/test/unit/issues.test.js b/test/unit/issues.test.js
index df9abf4da..5fd2e9a0c 100644
--- a/test/unit/issues.test.js
+++ b/test/unit/issues.test.js
@@ -630,4 +630,32 @@ describe('issues', () => {
       VueI18n.prototype.getChoiceIndex = defaultImpl
     })
   })
+
+  describe('#484', () => {
+    it('passes path to the formatter', () => {
+      const testPath = 'test.deep.message'
+
+      i18n = new VueI18n({
+        locale: 'en',
+        messages: {
+          en: {
+            test: {
+              deep: {
+                message: 'Hello!'
+              }
+            }
+          }
+        },
+        formatter: {
+          interpolate (message, values, path) {
+            assert(path, testPath)
+
+            return null // pass the case to the default formatter
+          }
+        }
+      })
+
+      assert(i18n.t(testPath), 'Hello!')
+    })
+  })
 })
diff --git a/types/index.d.ts b/types/index.d.ts
index 59b318f77..496e1b178 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -70,7 +70,7 @@ declare namespace VueI18n {
   };
 
   interface Formatter {
-    interpolate(message: string, values?: Values): any[];
+    interpolate(message: string, values: Values | undefined, path: string): (any[] | null);
   }
 
   type MissingHandler = (locale: Locale, key: Path, vm?: Vue) => string | void;