Ionic3/Ngx-translate - 带有外部 URL 的 TranslateHttpLoader [英] Ionic3 / Ngx-translate - TranslateHttpLoader with external URL

问题描述

我正在使用我的 app.module.ts 中的 TranslateHttpLoader 从服务器加载翻译文件，如下所示:

I'm loading the translation files from the server using TranslateHttpLoader in my app.module.ts like this:

export function createTranslateLoader(http: Http) {
   return new TranslateHttpLoader(http, AppConfig.API_URL+'/static/i18n/', '.json');
}

@NgModule({
  ...

  imports: [

    TranslateModule.forRoot({
      loader: {
        provide: TranslateLoader,
        useFactory: (createTranslateLoader),
        deps: [Http]
      }
    }), 

  ],
  ...
})

一切正常，但我想知道是否有办法在加载程序因任何原因(服务器问题、网络配置等)未能检索语言文件时捕获事件，并可能加载带有一些的本地 json 文件默认翻译字符串?

Everything works fine, but i'm wondering if there is a way to catch event when the loader fails to retrieve the language file for whatever reason (server issues, net con etc.) and possibly load a local json file with some default translation strings?

如果第一次加载的应用程序无法获取语言文件，我想捕获此事件，并回退到最小的本地 json 文件以仅显示翻译的维护页面/错误页面或其他内容.

I want to catch this event if the app on the first load fails to grab the language file , and fallback to minimal local json file to just display translated mainetnance page/error page or something.

推荐答案

UPDATE for Angular >= 4.3

由于新的 Angular 版本使用 HttpClient 而不是 Http，这是 mike_t 的 CustomTranslateLoader 将是:

As new Angular versions use HttpClient instead of Http, an updated and much shorter version of mike_t's CustomTranslateLoader would be:

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { TranslateLoader } from '@ngx-translate/core';
import { Observable } from 'rxjs/Observable';
import { catchError } from 'rxjs/operators';
import { AppConfig } from './config';


@Injectable()
export class CustomTranslateLoader implements TranslateLoader  {
    contentHeader = new HttpHeaders({
      'Content-Type': 'application/json',
      'Access-Control-Allow-Origin': '*',
    });

    constructor(private httpClient: HttpClient) {}
    getTranslation(lang: string): Observable<any> {
        const apiAddress = AppConfig.API_URL + `/static/i18n/${lang}.json`;
        return this.httpClient.get(apiAddress, { headers: this.contentHeader })
          .pipe(
            catchError(_ => this.httpClient.get(`/assets/i18n/en.json`))
          );
    }
}

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