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translation.service.md

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Title Added Status Last reviewed
Translation service
v2.0.0
Active
2019-02-08

Translation service

Supports localisation.

Class members

Methods

  • addTranslationFolder(name: string = "", path: string = "")
    Adds a new folder of translation source files.
    • name: string - Name for the translation provider
    • path: string - Path to the folder
  • get(key: string|Array<string>, interpolateParams?: Object): Observable<string|any>
    Gets the translation for the supplied key.
    • key: string|Array<string> - Key to translate
    • interpolateParams: Object - (Optional) String(s) to be interpolated into the main message
    • Returns Observable<string|any> - Translated text
  • instant(key: string|Array<string>, interpolateParams?: Object): string|any
    Directly returns the translation for the supplied key.
    • key: string|Array<string> - Key to translate
    • interpolateParams: Object - (Optional) String(s) to be interpolated into the main message
    • Returns string|any - Translated text
  • loadTranslation(lang: string, fallback?: string)
    Loads a translation file.
    • lang: string - Language code for the language to load
    • fallback: string - (Optional) Language code to fall back to if the first one was unavailable
  • onTranslationChanged(lang: string)
    Triggers a notification callback when the translation language changes.
    • lang: string - The new language code
  • use(lang: string): Observable<any>
    Sets the target language for translations.
    • lang: string - Code name for the language
    • Returns Observable<any> - Translations available for the language

Details

In the get and instant methods, the interpolateParams parameter supplies interpolation strings for keys that include them. For example, in the standard en.json, the CORE.PAGINATION.ITEMS_RANGE key is defined as:

"Showing {{ range }} of {{ total }}"

The range and total interpolations are supplied to the get method using an object with fields of the same name:

this.trans.get(
      "CORE.PAGINATION.ITEMS_RANGE",
      {
        range: "1..10",
        total: "122"
      }
    ).subscribe(translation => {
      this.translatedText = translation;
    });

Registering translation sources

To supply your own set of translation source files, you first need to create a subfolder for them within your application's assets folder. The folder can have any name you like but it must also have a sub-folder called i18n where the translation lists will be stored. So, the general format of the path to this folder will be:

<app>/src/assets/my-translations/i18n

If you wanted English and French translations then you would add en.json and fr.json files into the i18n folder and add your new keys:

// en.json

    ...
  "WELCOME_MESSAGE": "Welcome!"
    ...

// fr.json
    ...
  "WELCOME_MESSAGE": "Bienvenue !"
    ...

The files follow the same hierarchical key:value JSON format as the built-in translations. You can add new keys to your local files or redefine existing keys but the built-in definitions will be used for any keys you don't explicitly define in your files. For example, en.json might look like the following:

{
  "title": "my app",
  "LOGIN": {
     "LABEL": {
        "LOGIN": "Custom Sign In"
     }
  }
}

To enable the new translations in your app, you also need to register them in your app.module.ts file. Import TRANSLATION_PROVIDER and add the path of your translations folder to the providers:

// Other imports...

import { TRANSLATION_PROVIDER } from "@alfresco/adf-core";

  ...

@NgModule({
  imports: [
    ...
  ],
  declarations: [
    ...
  ],
  providers: [
    {
      provide: TRANSLATION_PROVIDER,
      multi: true,
      useValue: {
          name: 'my-translations',
          source: 'assets/my-translations'
      }
  }
  ...

You can now use your new keys in your component:

  ...
ngOnInit() {
    this.trans.use("fr");
    
    this.trans.get("WELCOME_MESSAGE").subscribe(translation => {
      this.translatedText = translation;
    });
  }
  ...

Note: the source property points to the web application root. Ensure you have webpack correctly set up to copy all the i18n files at compile time.

index.html
assets/ng2-alfresco-core/i18n/en.json
...

You can register as many entries as you like.

Switching languages

Depending on your application, you may want to have buttons or dropdown menus to allow language selection for the end users.

You can use TranslationService to switch languages from your code based on input events of your choice:

class MyComponent {
    constructor(private translateService: TranslationService) {
    }

    onLanguageClicked(lang: string) {
        this.translateService.use(lang || 'en');
    }
}

See Also