/ng2-translate

An implementation of angular translate for Angular 2

Primary LanguageTypeScript

ng2-translate Build Status npm version

An implementation of angular translate for Angular 2.

Simple examples using ng2-translate:

Installation

First you need to install the npm module:

npm install ng2-translate --save

If you use SystemJS to load your files, you might have to update your config with this if you don't use defaultJSExtensions: true:

System.config({
    packages: {
        "/ng2-translate": {"defaultExtension": "js"}
    }
});

Finally, you can use ng2-translate in your Angular 2 project (make sure that you've loaded the angular2/http bundle as well). It is recommended to instantiate TranslateService in the bootstrap of your application and to never add it to the "providers" property of your components, this way you will keep it as a singleton. If you add it to the "providers" property of a component it will instantiate a new instance of the service that won't be initialized.

import {HTTP_PROVIDERS} from 'angular2/http';
import {Component, Injectable, provide} from 'angular2/core';
import {TranslateService, TranslatePipe, TranslateLoader, TranslateStaticLoader} from 'ng2-translate/ng2-translate';
import {bootstrap} from 'angular2/platform/browser';

bootstrap(AppComponent, [
    HTTP_PROVIDERS,
    // not required if you use TranslateStaticLoader (default)
    // use this if you want to use another loader
    provide(TranslateLoader, {useClass: TranslateStaticLoader}),
    // not required, but recommended to have 1 unique instance of your service
    TranslateService
]);

@Injectable()
@Component({
    selector: 'app',
    template: `
        <div>{{ 'HELLO' | translate:{value: param} }}</div>
    `,
    pipes: [TranslatePipe]
})
export class AppComponent {
    param: string = "world";

    constructor(translate: TranslateService) {
        var userLang = navigator.language.split('-')[0]; // use navigator lang if available
        userLang = /(fr|en)/gi.test(userLang) ? userLang : 'en';

         // this language will be used as a fallback when a translation isn't found in the current language
        translate.setDefaultLang('en');

         // the lang to use, if the lang isn't available, it will use the current loader to get them
        translate.use(userLang);
    }
}

For now, only the static loader is available. You can configure it like this:

var prefix = 'assets/i18n';
var suffix = '.json';
translate.useStaticFilesLoader(prefix, suffix);

Then put your translations in a json file that looks like this (for en.json):

{
    "HELLO": "hello {{value}}"
}

An then you can get new translations like this:

    translate.getTranslation(userLang);

But you can also define your translations manually instead of using getTranslation:

translate.setTranslation('en', {
    "HELLO": "hello {{value}}"
});

API

TranslateService

Properties:

  • currentLang: The lang currently used

  • currentLoader: An instance of the loader currently used (static loader by default)

  • onLangChange: An EventEmitter to listen to lang changes events

    example:

     onLangChange.subscribe((params: {lang: string, translations: any}) => {
   // do something
 });

Methods:

  • useStaticFilesLoader(): Use a static files loader
  • useLoader(loader: TranslateLoader): Use a different loader
  • setDefaultLang(lang: string): Sets the default language to use as a fallback
  • use(lang: string): Observable<any>: Changes the lang currently used
  • getTranslation(lang: string): Observable<any>: Gets an object of translations for a given language with the current loader
  • setTranslation(lang: string, translations: Object): Manually sets an object of translations for a given language
  • setMissingTranslationHandler(handler: MissingTranslationHandler): void: sets the Missing Translation Handler which will be used when the requested translation is not available
  • getLangs(): Returns an array of currently available langs
  • get(key: string|Array<string>, interpolateParams?: Object): Observable<string|Object>: Gets the translated value of a key (or an array of keys)
  • instant(key: string|Array<string>, interpolateParams?: Object): string|Object: Gets the instant translated value of a key (or an array of keys)
  • set(key: string, value: string, lang?: string): set the translated value of a key

Write & use your own loader

If you want to write your own loader, you need to create a class that implements TranslateLoader. The only required method is getTranslation that must return an Observable. If your loader is synchronous, just use Observable.of to create an observable from your static value.

Example
class CustomLoader implements TranslateLoader {
    getTranslation(lang: string): Observable<any> {
        return Observable.of({"KEY": "Value"});
    }
}

Once you've defined your loader, you can provide it in bootstrap:

bootstrap(AppComponent, [
    HTTP_PROVIDERS,
    provide(TranslateLoader, {useClass: CustomLoader}),
    TranslateService
]);

Or you can just use the useLoader method:

export class AppComponent {
    constructor(translate: TranslateService, myLoader: CustomLoader) {
        translate.useLoader(myLoader);
    }
}

How to handle missing translations

You can use the method setMissingTranslationHandler to define a handler that will be called when the requested translation is not available. The only required method is handle where you can do whatever you want. Just don't forget that it will be called synchronously from the get & instant methods.

Example:

Create a Missing Translation Handler

import {MissingTranslationHandler} from 'ng2-translate/ng2-translate';

export class MyMissingTranslationHandler implements MissingTranslationHandler {
  handle(key: string) {
      console.log(key);
  }
}

Set the Missing Translation Handler

constructor(translate: TranslateService) {
  ...
  translate.setMissingTranslationHandler(new MyMissingTranslationHandler());
  ...
}

TranslatePipe

You can call the TranslatePipe with some optional parameters that will be transpolated into the translation for the given key.

Example:

<p>Say {{ 'HELLO' | translate:{value: "world"} }}</p>

With the given translation: "HELLO": "hello {{value}}".

Parser

Methods:

  • interpolate(expr: string, params?: any): string: Interpolates a string to replace parameters.

    This is a {{ key }} ==> This is a value with params = { key: "value" }

  • flattenObject(target: Object): Object: Flattens an object { key1: { keyA: 'valueI' }} ==> { 'key1.keyA': 'valueI' }