Comparing fields in validator with angular2

Question

I am trying to create a registration form in Angular2, having a "repeat password" functionality. I want this to work using a custom validator as a form-control.

The problem I am having is that the "this-context" seems to be set to the validator when the validator is running so I cant access any local methods on the RegistrationForm class. And I can't seem to find any good way to access the ControlGroup from the validator.

Anyone know a good way to access other controls in the same control-group inside a custom validator?

The is a short sample of the component:

import { Component, View } from 'angular2/angular2';
import { Validators, ControlGroup, Control, FORM_DIRECTIVES, FORM_BINDINGS } from 'angular2/angular2';

@Component({
    selector: 'form-registration'
})
@View({
    directives: [FORM_DIRECTIVES, ROUTER_DIRECTIVES],
    template: `
        <form (submit)="register($event)" [ng-form-model]="registerForm">
            <label for="password1">Password:</label>
            <input id="password1" ng-control="password1" type="password" placeholder="Passord" />

            <label for="password2">Repeat password:</label>
            <input id="password2" ng-control="password2" type="password" placeholder="Gjenta passord" />

            <button class="knapp-submit" type="submit" [disabled]="!registerForm.valid">Registrer deg</button>
        </form>
    `
})
export class RegistrationForm {
    registerForm: ControlGroup;

    constructor() {            
        this.registerForm = new ControlGroup({
            password1: new Control('', Validators.required),
            password2: new Control('', this.customValidator)
        });
    }

    public register(event: Event) {
        // submit form
    }

    private customValidator(control: Control) {
        // check if control is equal to the password1 control
        return {isEqual: control.value === this.registerForm.controls['password1'].value};
    }
}

Answer 1

So I solved the problem by binding the customValidator to the this-context of my class as explained in the comment by Sergio.

Keep in mind that the .bind(this) function returns a new instance of the function with the bound-context.

import { Component, View } from 'angular2/angular2';
import { Validators, ControlGroup, Control, FORM_DIRECTIVES, FORM_BINDINGS } from 'angular2/angular2';

@Component({
    selector: 'form-registration'
})
@View({
    directives: [FORM_DIRECTIVES, ROUTER_DIRECTIVES],
    template: `...my form template...`
})
export class RegistrationForm {
    registerForm: ControlGroup;

    constructor() {           
        this.customValidator = this.customValidator.bind(this); 
        this.registerForm = new ControlGroup({
            password1: new Control('', Validators.required),
            password2: new Control('', this.customValidator)
        });
    }

    public register(event: Event) {
        // submit form
    }

    private customValidator(control: Control) {
        // check if control is equal to the password1 control
        return {isEqual: control.value === this.registerForm.controls['password1'].value};
    }
}