Validation is not propagate to Custom Form Control ng-select in Angular

问题

I'm using Reactive Form with Custom Form Control in my Angular 9 application.

I wrapped my ng-select control with Custom Form Control.

And I have problem with validation. I set formControl to be required. Documentation says that ng-invalid css class should be set to ng-select automatically. But in fact with custom form control it doesn't work properly. The css class is not set, but the wrapper class is. Am I doing something wrong or this is library issue?

Check stackblitz: https://stackblitz.com/edit/angular-rmvttg-ex63ka?file=src/forms-single-select-example.component.html&fbclid=IwAR2robtd_15khTVhmW59lLhn21HOHl_yYTrCWKaPRmfUt1QVvUn3n8V4Vjo

回答1:

DiPix, the problem is that Angular add the control status CSS classes to your custom control, NOT to the ng-select that belong to your inner control

You can inject the ngControl and check about control.control.invalid and control.control.touched

constructor(private injector:Injector){}
ngOnInit()
{
   this.control = this.injector.get(NgControl);
}

then you can use some like

  <ng-select #mySelect  [ngClass]="{'ng-invalid':control?.control.invalid,
                                    'ng-touched':control?.control.touched}"
   ....>

Another aproach is ask about the class of the parent. So if you defined a getter like

get parentClass()
{
  const match = /class=\"(.*?)\">/.exec(this.element.nativeElement.parentElement.innerHTML);
  return match[0].split('"')[1]
}

constructor(private element:ElementRef){}

You can use

<ng-select #mySelect  [ngClass]="parentClass" 
  ...>

You can see in your forked stackblitz

NOTE: Anyway, to wrapper a ng-select, is unnecesary create a custom form control, just a simple component with a @Input

@Input()control:any

And you use as

    <mycontrol [control]="someForm.get('someControl')"></mycontrol>

You can see how simple becomes in this another stackblitz

回答2:

You can fix this by passing the FormGroup down into your subcomponent via Input and set it to the ng-select:

<mycontrol formControlName="someControl" [parentFormGroup]="someForm" ></mycontrol>

Component:

export class MyControlComponent implements ControlValueAccessor {

  @Input() parentFormGroup: FormGroup;
...

Template:

<ng-select #mySelect
           [formGroup]="parentFormGroup"
...

来源：https://stackoverflow.com/questions/60459025/validation-is-not-propagate-to-custom-form-control-ng-select-in-angular

标签

angular

typescript

angular-reactive-forms

angular-ngselect