Question

所以我的服务中有一个函数返回一个值，我希望我的组件监听该值并在它发生变化时更新它，所以我认为订阅它是个好主意，但它没有按预期工作，并且在更改时不会更新值。有没有其他方法可以做到这一点？

 ngOnInit(): void {
    this.translateService.onLangChange.subscribe(() => this.getLocaleDateFormat());
  }

 getLocaleDateFormat(): Observable<string> {
   this.dateAdapter.setLocale(Languages[this.translateService.currentLang]);
   this.currLang = Languages[this.translateService.currentLang];
    console.log( 'get' + this.currLang);
    return of (this.currLang);

  }

ngOnInit(): void {
    this.localeDateAdapterService.getLocaleDateFormat().subscribe(currLang => this.currLang = currLang);
}

我不需要知道它什么时候改变，我只需要知道它改变时要更新的值。不使用计时器，也不使用 OnLangChange 作为触发器：

ngOnInit(): void {
 this.translateService.onLangChange.subscribe(() => this.localeDateAdapterService.getLocaleDateFormat().subscribe(currLang => this.currLang = currLang));
}

Answer 1

使用来自 /rxjs

的主题

// Service

language$ = new Subject<string>();

setLanguage(lang: string): void {
 this.language$.next(lang);
}


// Component

this.language$.subscribe((res: string) => {
 console.log(res);
});

this.languageSrv.setLanguage('en');
this.languageSrv.setLanguage('es');
this.languageSrv.setLanguage('it');
this.languageSrv.setLanguage('fr');

// 'en'
// 'es'
// 'it'
// 'fr'

记得退订

Answer 2

我将其作为名为 LocaleService 的单独服务制作。您必须以某种方式获取当前语言，可能来自翻译服务，或者您将其作为处理它的单独服务。

Task.Wait

这去组件

private onLanguageChange(lang: string): void {
        // To add another lang:
        // 1. add mapping from EMS language codes to Angular locale codes in the map at the bottom of this file
        // 2. register locale data, also at the bottom of this file
        const locale = Languages[lang];
        this.activeLocale.next(locale);
        this.dateAdapter.setLocale(locale);
        this.LW.log('Language change detected (current lang: ' + lang + '), setting locale to: ' + locale);
      }
    
      public getActiveLocale(): BehaviorSubject<string> {
        return this.activeLocale;
      }
    export const Languages = {
      'eng': 'en',
      'slk': 'sk',
      'cze': 'cs',
    };
    
    registerLocaleData(localeSk);
    registerLocaleData(localeCs);

Angular 监听返回一些变量的函数

2 个答案: