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/Angular 7

MaxLengthValidator

directive

A directive that adds max length validation to controls marked with the maxlength attribute. The directive is provided with the NG_VALIDATORS multi-provider list.

See also

NgModules

Selectors

Properties

Property Description
@Input()maxlength: string

Tracks changes to the the maximum length bound to this directive.

Description

Adding a maximum length validator

The following example shows how to add a maximum length validator to an input attached to an ngModel binding.

<input name="firstName" ngModel maxlength="25">

Methods

A lifecycle method called when the directive's inputs change. For internal use only.

ngOnChanges(changes: SimpleChanges): void

Parameters
changes SimpleChanges

A object of key/value pairs for the set of changed inputs.

Returns

void

Method that validates whether the value exceeds the maximum length requirement.

validate(control: AbstractControl): ValidationErrors | null

Parameters
control AbstractControl
Returns

ValidationErrors | null

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://v7.angular.io/api/forms/MaxLengthValidator