CODEWITHSUNDEEP
angularangular9
Sam
Sam

Reputation: 14596

Angular Parent Component property does not get updated when changing value from Child Component

Below I don't understand why I'm getting the compilation error Cannot use variable 'ft' as the left-hand side of an assignment expression. Template variables are read-only.

If I remove the banana-syntax and leave it as [fileType], then I have no errors, but when I change the value from the Select control in the child component, the item in the parent collection fileTypes does not get updated. How should I do it so the parent collection gets updated ?

parent component

<app-file-type-list-item class="form-row align-items-end" *ngFor="let ft of fileTypes" [(fileType)]="ft"></app-file-type-list-item>

child component

<select name="fileType01" id="fileType01" [(ngModel)]="fileType" (change)="onFileTypeChange()">
 <option *ngFor="let fileType of fileTypes" [ngValue]="fileType">
       {{fileType.name}}</option>
</select>


export class FileTypeListItemComponent {


  @Input() public fileType: FileType;
 
  @Output() fileTypeChange = new EventEmitter();


  public fileTypes;

  constructor(private _entityManagerService: POPEntityManagerService) {
    this.fileTypes = // filled from datasource
    
  onFileTypeChange(): void {
    this.fileTypeChange.emit(this.fileType);
  }
}

Upvotes: 2

Views: 411

Answers (1)

Vlad B.
Vlad B.

Reputation: 2937

Can you try using this syntax:

<app-file-type-list-item class="form-row align-items-end" *ngFor="let ft of fileTypes; let i = index" [(fileType)]="fileTypes[i]"></app-file-type-list-item>

In case if it doesnt work plesase provide details for Angular compiler options in case these options are not enabled

"fullTemplateTypeCheck": true,
"strictInjectionParameters": true

Upvotes: 4

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