Using Firebase with the async pipe in Angular 5

Question

Using Firebase with the async pipe in Angular 5

I am struggling to implement async pipe in Angular firebase and encountering an error that I cannot resolve:

ERROR Error: InvalidPipeArgument: '[object Object]' for pipe 'AsyncPipe'

Utilizing the Firebase NoSQL database:

{
  "boss" : [ null, {
    "isPremium" : true,
    "name" : "John",
    "students" : 10000
  } ],
  "users" : [ null, "user", "user2" ]
}

LATEST UPDATE

I have made changes to the component code:

user$: AngularFireList<any>;

  constructor(database: AngularFireDatabase) {
    this.user$ = database.list("/users");
  }

Here is the corresponding html:

<ul>
  <li *ngFor="let user of user$ | async">
    {{ user }}
  </li>
</ul>

The same error persists... It seemed to work fine in Angular version 4, but how can I resolve it in angular 5.2.0 ??

html angular

Answer 1

Answer №1

The concept of using the async pipe revolves around working with observables as parameter inputs. If you encounter an error stating that the user$ field is not considered an observable, it may be worth reviewing if you intended to subscribe to the valueChanges() observable associated with the db.object() method instead.

For further insights, explore this resource: https://github.com/angular/angularfire2/blob/master/docs/rtdb/objects.md

UPDATE

Upon examination, it appears that AngularFireList<any> does not qualify as an Observable, leading to the same type of error being prompted.

According to the documentation within angularfire2, the list() function now generates an object in the most recent version, which incorporates a valueChanges() method. It might prove beneficial to modify the code by invoking the valueChanges() function and utilizing the async pipe on the resultant observable.

Further elaboration can be found here: https://github.com/angular/angularfire2/blob/master/docs/version-5-upgrade.md#50

Answer 2

The concept of using the async pipe revolves around working with observables as parameter inputs. If you encounter an error stating that the user$ field is not considered an observable, it may be worth reviewing if you intended to subscribe to the valueChanges() observable associated with the db.object() method instead.

For further insights, explore this resource: https://github.com/angular/angularfire2/blob/master/docs/rtdb/objects.md

UPDATE

Upon examination, it appears that AngularFireList<any> does not qualify as an Observable, leading to the same type of error being prompted.

According to the documentation within angularfire2, the list() function now generates an object in the most recent version, which incorporates a valueChanges() method. It might prove beneficial to modify the code by invoking the valueChanges() function and utilizing the async pipe on the resultant observable.

Further elaboration can be found here: https://github.com/angular/angularfire2/blob/master/docs/version-5-upgrade.md#50

Answer 3

Answer №2

You're getting that error because, async pipe works with Observables and the data you're returning is not.

You might want to change your code to this:

user$: Observable<any[]>;

  constructor(db: AngularFireDatabase) {
    this.user$ = db.list("/users").snapshotChanges();
  }

Or this:

constructor(db: AngularFireDatabase) {
   this.user$ = db.list("/users").valueChanges();
}

Answer 4

You're getting that error because, async pipe works with Observables and the data you're returning is not.

You might want to change your code to this:

user$: Observable<any[]>;

  constructor(db: AngularFireDatabase) {
    this.user$ = db.list("/users").snapshotChanges();
  }

Or this:

constructor(db: AngularFireDatabase) {
   this.user$ = db.list("/users").valueChanges();
}

Using Firebase with the async pipe in Angular 5

Answer №1

Answer №2

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