angular2 async validation this.subscribe exception?

问题

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>...

回答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])],

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.

来源：https://stackoverflow.com/questions/40781775/angular2-async-validation-this-subscribe-exception

标签

angular2-forms