@angular/forms

NG_ASYNC_VALIDATORS

constant

stable

An InjectionToken for registering additional asynchronous validators used with AbstractControls.

API

  const NG_ASYNC_VALIDATORS: InjectionToken<readonly (Function | Validator)[]>;

Usage Notes

Provide a custom async validator directive

The following example implements the AsyncValidator interface to create an async validator directive with a custom error key.

@Directive({ selector: '[customAsyncValidator]', providers: [{provide: NG_ASYNC_VALIDATORS, useExisting: CustomAsyncValidatorDirective, multi:true}]})class CustomAsyncValidatorDirective implements AsyncValidator { validate(control: AbstractControl): Promise<ValidationErrors|null> { return Promise.resolve({'custom': true}); }}