@Directive({ selector: '[appForbiddenName]', providers: [{provide: NG_VALIDATORS, useExisting: ForbiddenValidatorDirective, multi: true}] }) export class ForbiddenValidatorDirective implements Validator { @Input('appForbiddenName') forbiddenName: string; validate(control: AbstractControl): {[key: string]: any} | null { return this.forbiddenName ? forbiddenNameValidator(new RegExp(this.forbiddenName, 'i'))(control) : null; } }