The ControlValueAccessor for writing multi-select control values and listening to multi-select control changes. The value accessor is used by the FormControlDirective, FormControlName, and NgModel directives.

See also

• SelectControlValueAccessor

Exported from

• ReactiveFormsModule

• FormsModule

Selectors

• select[multiple][formControlName]
• select[multiple][formControl]
• select[multiple][ngModel]

Properties

Property	Description
@Input()compareWith: (o1: any, o2: any) => boolean	Write-Only Tracks the option comparison algorithm for tracking identities when checking for changes.

Description

Using a multi-select control

The follow example shows you how to use a multi-select control with a reactive form.

const countryControl = new FormControl();

<select multiple name="countries" [formControl]="countryControl">
  <option *ngFor="let country of countries" [ngValue]="country">
    {{ country.name }}
  </option>
</select>

Customizing option selection

To customize the default option comparison algorithm, <select> supports compareWith input. See the SelectControlValueAccessor for usage.

Methods

registerOnChange()
registerOnChange(fn: (value: any) => any): void Parameters fn (value: any) => any Returns void