管道'AsyncPipe'的InvalidPipeArgument:'[object Object]'

Question

在服务中声明如下:

public currentDBUserBS$: any;

constructor(private afDb: AngularFireDatabase){}

fetchUser(uid){
  this.afDb.object(`users/${uid}`).valueChanges().subscribe((dUser) => {
    if (dUser) {
      this.currentDBUserBS$ = dUser;
    }
  });
}

现在尝试在模板中使用

template: `<li *ngIf="(authService.currentDBUserBS$ | async)?.role=='admin'"> Something </li>`

错误堆栈:

ERROR Error: InvalidPipeArgument: '[object Object]' for pipe 'AsyncPipe'
    at invalidPipeArgumentError (common.js:4219)
    at AsyncPipe._selectStrategy (common.js:5630)
    at AsyncPipe._subscribe (common.js:5612)
    at AsyncPipe.transform (common.js:5586)
    at Object.View_AppNavigatorComponent_0._co [as updateDirectives] (AppNavigatorComponent.html:40)
    at Object.debugUpdateDirectives [as updateDirectives] (core.js:14339)
    at checkAndUpdateView (core.js:13508)
    at callViewAction (core.js:13858)
    at execComponentViewsAction (core.js:13790)
    at checkAndUpdateView (core.js:13514)

Answer 1

您正在currentDBUserBS$从Firebase获取对象,而不是Observable.如果您想这样做,则必须删除| async模板中的内容.

但是,您可以执行以下操作:

fetchUser(uid){
  this.currentDBUserBS$ = this.afDb.object(`users/${uid}`).valueChanges();
}

.valueChanges() 为您提供可观察的,并在发出新值或修改现有值时自动更新.