Which @angular/* package(s) are relevant/related to the feature request?

forms

Description

I'd like to be able to show a required asterisk (*) when the Validators.required is added to the reactive forms control.

There doesn't seem to be a way to get this information in any rxjs event or signal way.

My only workaround is to subscribe to formControl.events, but this ends up with extra noise and is not immediately triggered if changing from one invalid reason to another, etc.

Proposed solution

AbstractControl<any, any>.events: Observable<ControlEvent<any>> should be extended to include a ValidatorsChangeEvent

export declare class ValidatorsChangeEvent extends ControlEvent {
    readonly validators: ValidatorFn[];
    readonly source: AbstractControl;
    constructor(validators: ValidatorFn[], source: AbstractControl);
}

Alternatives considered

The following doesn't work very well:

const sub = formControl.events
.pipe(
  takeUntilDestroyed(this.destroyRef),
  map((x) => formControl.hasValidator(Validators.required)),
  // only trigger when the value changes
  distinctUntilChanged(
    (a, b) => a === b,
    (x) => x,
  ),
)
.subscribe((isFormControlRequired) => {