validation - Inject a service in a custom validator in Angular2 -

i try use service in custom validator check if username exists.

import {component} 'angular2/core'; import {     control,     controlgroup,     formbuilder } "angular2/common"; import {characterservice} "./character-service";  @component({     selector: 'register-character-form',     template: `         <h2 class="ui header">a new adventurer coming...</h2>         <form (ngsubmit)="register()" [ngformmodel]="characterform" class="ui form">             <div class="field">                 <label>nom</label>                 <input ngcontrol="name">             </div>             <button type="submit" class="ui button">enter in adventure</button>         </form>     `,     providers: [characterservice] }) export class registercharacterformcmp {     characterform: controlgroup;     name: control;      constructor(private _characterservice: characterservice, fb: formbuilder) {         this.name = fb.control('', this.characternamevalidator);          this.characterform = fb.group({             name: this.name         });     }      register(): void {         //todo: implement     }      // not works, binds control     characternamevalidator(control: control) {         return this._characterservice.ischaracternamealreadyexists(control.value) ? {namecharacteralreadyexistserror: true} : null;     } } 

it doesn't work. in characternamevalidator, 'this' references control , not class. service undefined. how can use service in validator ?

more globally, how can pass arguments in custom validator ?

you need control this means in validation. can bind

this.name = fb.control('', this.characternamevalidator.bind(this)); 

everything else should work expected then.