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angular / 9 / api / forms / requiredvalidator.html

RequiredValidator

directive

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

NgModules

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

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Licensed under the Creative Commons Attribution License 4.0.
https://v9.angular.io/api/forms/RequiredValidator