angular2 async validation this.subscribe exception? - angular2-forms

Question

I try to implement async(isUnique) and sync(cannotContainSpace) validation functions for username field, I want to see "this username already in use alert msg, if textbox value is "yener". sync function works fine but i think ss below can help explain my issue;
Note:canNotContain sync validation func works fine, aafter I added isUnique async function this exception occured..
how can I fix it ?
usernamevalidator.ts
import {FormControl} from '#angular/forms';
export class UsernameValidator{
static isUnique(control:FormControl){
return new Promise((resolve, reject)=>{
setTimeout(function(){
debugger
if(control.value =="yener")
resolve({isUnique:true})
else
resolve(null)
},1000);
});
}
static cannotContainSpace(control:FormControl){
if(control.value.indexOf(' ')>=0)
return { cannotContainSpace:true };
return null;
}
}
postmessage.component.ts
import { Component } from '#angular/core';
import {FormControl,FormGroup,FormBuilder,Validators} from '#angular/forms';
import {UsernameValidator} from '../../validators/usernamevalidator';
#Component({
moduleId:module.id,
selector: 'post-message',
templateUrl: '../../templates/postmessage.component.html'
})
export class PostComponent {
form : FormGroup;
constructor(fb:FormBuilder){
this.form = fb.group({
username:['', Validators.compose([Validators.required, UsernameValidator.cannotContainSpace]),Validators.compose([UsernameValidator.isUnique])],
email:['', Validators.required],
message:['', Validators.required]
});
}
signup(){
console.log(this.form.value);
}
}
here is html template:
<form class="from-horizontal" [formGroup]="form" (ngSubmit)="signup()">
<div class="form-group row">
<label for="username" class="control-label col-md-2">Name:</label>
<div class="col-md-6">
<input type="text" id="username" class="form-control" formControlName="username">
<div *ngIf="form.controls['username'].touched && form.controls['username'].errors">
<div class="alert alert-danger"
*ngIf="form.controls['username'].errors.required">
User name is required.
</div>
<div class="alert alert-danger"
*ngIf="form.controls['username'].errors.cannotContainSpace">
User name can not contain space
</div>
<div class="alert alert-danger" *ngIf="form.controls['username'].errors.isUnique">
This user name already in use.
</div>
</div>
</div>...

Answer 1

it's strange, i though we can use "Validators.compose()" function in form builder initializer as async parameters but angular2 dont agree with me..
I just changed;
username:['', Validators.compose([Validators.required,
UsernameValidator.cannotContainSpace]),Validators.compose([UsernameValidator.isUnique])],
to
username:['', Validators.compose([Validators.required,
UsernameValidator.cannotContainSpace]),UsernameValidator.isUnique],
and it works
EDITED:
also I figured out if you want to use multiple async validators in a component use
Validators.composeAsync()
function.