RequiredValidator

A directive that adds the required validator to any controls marked with the required attribute. The directive is provided with the NG_VALIDATORS multi-provider list.

See also

• Form Validation

NgModules

• FormsModule

• ReactiveFormsModule

Selectors

• :not([type=checkbox])[required][formControlName]
• :not([type=checkbox])[required][formControl]
• :not([type=checkbox])[required][ngModel]

Properties

Property	Description
@Input()required: boolean | string	Tracks changes to the required attribute bound to this directive.

Description

Adding a required validator using template-driven forms

<input name="fullName" ngModel required>

Methods

validate()
Method that validates whether the control is empty. Returns the validation result if enabled, otherwise null.
validate(control: AbstractControl): ValidationErrors | null Parameters control AbstractControl Returns ValidationErrors | null

registerOnValidatorChange()
Registers a callback function to call when the validator inputs change.
registerOnValidatorChange(fn: () => void): void Parameters fn () => void The callback function Returns void