Angular FormArray setValue with data from Service

Question

I have a Problem with FormArray and could need some help. I have a form with variable FormArray and it works and I can send the data to the backend. The problem is, that I cant set the values from the data I receive from the backend.

This is the Typescript Code:

this.form = this.fb.group({
  title: new FormControl("",[Validators.required]),
  actors: new FormArray([])
})

this.moviesService.getMovie(this.movieId).subscribe(movieData => {
  this.movie = movieData;
  this.form.patchValue({
    title: this.movie.title,
    actors: this.movie.actors,           
  })
})

then on button click in html I call this functions:

addActor(){
  const actorsForm = this.fb.group({
    actor: '',
    role: ''
  })
  this.actors.push(actorsForm);
}

removeActor(i: number){
  this.actors.removeAt(i);
}

And the HTML:

<form [formGroup]="form" (submit)="onSubmit()">
  <table  formArrayName="actors">
    <tr>
      <th colspan="2">Besetzung:</th>
      <th width="150px">
        <button type="button" mat-stroked-button color="primary" (click)="addActor()">Hinzufügen +</button>
      </th>
    </tr>
    <tr *ngFor="let actor of form.get('actors')['controls']; let i=index" [formGroupName]="i">
      <td>
        Darsteller:
        <input type="text" formControlName="actor" class="form-control">
      </td>
      <td>
        Rolle:
        <input type="text" formControlName="role" class="form-control">
      </td>
      <td>
        <button (click)="removeActor(i)" mat-stroked-button color="warn">Remove</button>
      </td>
    </tr>
  </table>
  <button mat-raised-button color="primary" type="submit">Film speichern</button>
</form>

So my question is: How do I get the Data from the movieService in the actors Array?

actors: this.movie.actors doesn't work, I know I have to iterate through the array but don't know how.

Edit: Ok, I saw I got the first object from the array but if I add more actors it will just show the first.

Answer 1

Assumption:

Expected that the API response data received will be:

{
  "title": "James Bond 007",
  "actors": [
    { "id": 5, "role": "test", "actor": "test" },
    { "id": 6, "role": "test", "actor": "test2" }
  ]
}

---

I don't think that can directly patchValue for FormArray. Instead, iterate movie.actors with map in order to push FormGroup to actors FormArray.

this.movie.actors.map(
  (actor: any) => {
    const actorsForm = this.fb.group({
      actor: actor.actor,
      role: actor.role,
    });

    this.actors.push(actorsForm);
  }
);

this.form.patchValue({
  title: this.movie.title,
});

---

Note: Since you implement actors getter, you can simplify

form.get('actors')['controls']

to:

actors.controls

HTML

<tr
  *ngFor="let actor of actors.controls; let i = index"
  [formGroupName]="i"
>

</tr>

Sample Solution on StackBlitz