feat: add helpers to know if a message and a fallback message exists

adonis-typings/i18n.ts

@@ -218,6 +218,18 @@ declare module '@ioc:Adonis/Addons/I18n' {
       '*': ValidatorWildcardCallback
     }
 
+    /**
+     * Returns a boolean identifying if the message for a given
+     * identifier exists or not
+     */
+    hasMessage(identifier: string): boolean
+
+    /**
+     * Returns a boolean identifying if a fallback message for a given
+     * identifier exists or not
+     */
+    hasFallbackMessage(identifier: string): boolean
+
     /**
      * Format a message using its identifier. The message from the
      * fallback language is used when the message from current

src/I18n/index.ts

@@ -60,10 +60,10 @@ export class I18n extends Formatter implements I18nContract {
   }
 
   /**
-   * Lazy load messages. Doing this as i18n class usually results in switchLocale
+   * Lazy load translations. Doing this as i18n class usually results in switchLocale
    * during real world use cases
    */
-  private lazyLoadMessages() {
+  private lazyLoadTranslations() {
     if (!this.localeTranslations && !this.fallbackTranslations) {
       this.loadTranslations()
     }
@@ -135,6 +135,24 @@ export class I18n extends Formatter implements I18nContract {
     return this.formatRawMessage(message.message, data)
   }
 
+  /**
+   * Returns a boolean identifying if the message for a given
+   * identifier exists or not
+   */
+  public hasMessage(identifier: string): boolean {
+    this.lazyLoadTranslations()
+    return this.localeTranslations[identifier] !== undefined
+  }
+
+  /**
+   * Returns a boolean identifying if a fallback message for a given
+   * identifier exists or not
+   */
+  public hasFallbackMessage(identifier: string): boolean {
+    this.lazyLoadTranslations()
+    return this.fallbackTranslations[identifier] !== undefined
+  }
+
   /**
    * Switch locale for the current instance
    */
@@ -153,7 +171,7 @@ export class I18n extends Formatter implements I18nContract {
   } {
     return {
       '*': (field, rule, arrayExpressionPointer, options) => {
-        this.lazyLoadMessages()
+        this.lazyLoadTranslations()
         const data = { field, rule, options }
 
         /**
@@ -205,7 +223,7 @@ export class I18n extends Formatter implements I18nContract {
     data?: Record<string, any>,
     fallbackMessage?: string
   ): string {
-    this.lazyLoadMessages()
+    this.lazyLoadTranslations()
     const message = this.getMessage(identifier)
 
     /**

test/i18n.spec.ts

@@ -401,4 +401,66 @@ test.group('I18n | validatorBindings', (group) => {
       assert.deepEqual(error.messages, { username: ['username is required to signup'] })
     }
   })
+
+  test('find if a message exists', async (assert) => {
+    const app = await setup()
+    const emitter = app.container.resolveBinding('Adonis/Core/Event')
+    const logger = app.container.resolveBinding('Adonis/Core/Logger')
+
+    await fs.add(
+      'resources/lang/en/messages.json',
+      JSON.stringify({
+        greeting: '',
+      })
+    )
+
+    const i18nManager = new I18nManager(app, emitter, logger, {
+      defaultLocale: 'en',
+      translationsFormat: 'icu',
+      provideValidatorMessages: true,
+      loaders: {
+        fs: {
+          enabled: true,
+          location: join(fs.basePath, 'resources/lang'),
+        },
+      },
+    })
+
+    await i18nManager.loadTranslations()
+
+    const i18n = new I18n('en', emitter, logger, i18nManager)
+    assert.isTrue(i18n.hasMessage('messages.greeting'))
+    assert.isFalse(i18n.hasMessage('messages.title'))
+  })
+
+  test('find if a fallback message exists', async (assert) => {
+    const app = await setup()
+    const emitter = app.container.resolveBinding('Adonis/Core/Event')
+    const logger = app.container.resolveBinding('Adonis/Core/Logger')
+
+    await fs.add(
+      'resources/lang/en/messages.json',
+      JSON.stringify({
+        greeting: '',
+      })
+    )
+
+    const i18nManager = new I18nManager(app, emitter, logger, {
+      defaultLocale: 'en',
+      translationsFormat: 'icu',
+      provideValidatorMessages: true,
+      loaders: {
+        fs: {
+          enabled: true,
+          location: join(fs.basePath, 'resources/lang'),
+        },
+      },
+    })
+
+    await i18nManager.loadTranslations()
+
+    const i18n = new I18n('fr', emitter, logger, i18nManager)
+    assert.isFalse(i18n.hasMessage('messages.greeting'))
+    assert.isTrue(i18n.hasFallbackMessage('messages.greeting'))
+  })
 })