const
An InjectionToken
for registering additional synchronous validators used with AbstractControl
s.
const NG_VALIDATORS: InjectionToken<(Function | Validator)[]>;
The following example registers a custom validator directive. Adding the validator to the existing collection of validators requires the multi: true
option.
@Directive({ selector: '[customValidator]', providers: [{provide: NG_VALIDATORS, useExisting: CustomValidatorDirective, multi: true}] }) class CustomValidatorDirective implements Validator { validate(control: AbstractControl): ValidationErrors | null { return { 'custom': true }; } }
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https://v10.angular.io/api/forms/NG_VALIDATORS