angular2 异步表单验证

Question

我正在尝试使用 Angular2 完成表单验证。

我正尝试通过异步调用查明用户名是否已被占用并在我的数据库中使用。

到目前为止，这是我的代码:

表单组件:

import {Component, OnInit} from 'angular2/core';
import {FORM_PROVIDERS, Control, ControlGroup, FormBuilder, Validators} from 'angular2/common';
import {Http, Headers, RequestOptions} from 'angular2/http';
import {ROUTER_DIRECTIVES, Router, RouteParams} from 'angular2/router';
import {ControlMessages} from './control.messages';
import {ValidationService} from './validation.service';

@Component({
    selector: 'account-form',
    templateUrl: './app/account/account.form.component.html',
    providers: [ROUTER_DIRECTIVES, CaseDataService],
    directives: [ControlMessages]
})

accountForm: ControlGroup;

constructor(private _accountService: AccountDataService,
    private _formBuilder: FormBuilder, private _router: Router, private _params?: RouteParams) {
    this.model = this._accountService.getUser();

    this.accountForm = this._formBuilder.group({
        'firstName': ['', Validators.required],
        'lastName': ['', Validators.required],
        'userName': ['', Validators.compose([ValidationService.userNameValidator, ValidationService.userNameIsTaken])],

....
}

验证服务:

export class ValidationService {


static getValidatorErrorMessage(code: string) {
    let config = {
        'required': 'Required',
        'invalidEmailAddress': 'Invalid email address',
        'invalidPassword': 'Invalid password. Password must be at least 6 characters long, and contain a number.',
        'mismatchedPasswords': 'Passwords do not match.',
        'startsWithNumber': 'Username cannot start with a number.'
    };
    return config[code];
}

static userNameValidator(control, service, Headers) {
    // Username cannot start with a number
    if (!control.value.match(/^(?:[0-9])/)) {
        return null;
    } else {
        return { 'startsWithNumber': true };
    }
}
  // NEEDS TO BE AN ASYNC CALL TO DATABASE to check if userName exists. 
// COULD userNameIsTaken be combined with userNameValidator??

static userNameIsTaken(control: Control) {
    return new Promise(resolve => {
        let headers = new Headers();
        headers.append('Content-Type', 'application/json')

        // needs to call api route - _http will be my data service. How to include that?

        this._http.get('ROUTE GOES HERE', { headers: headers })
            .map(res => res.json())
            .subscribe(data => {
                console.log(data);
                if (data.userName == true) {
                    resolve({ taken: true })
                }
                else { resolve({ taken: false }); }
            })
    });
}
}

新代码(更新 x2)。 ControlGroup 返回未定义。

    this.form = this.accountForm;
    this.accountForm = this._formBuilder.group({
        'firstName': ['', Validators.required],
        'lastName': ['', Validators.required],
        'userName': ['', Validators.compose([Validators.required, this.accountValidationService.userNameValidator]), this.userNameIsTaken(this.form, 'userName')],
        'email': ['', Validators.compose([Validators.required, this.accountValidationService.emailValidator])],
        'password': ['', Validators.compose([Validators.required, this.accountValidationService.passwordValidator])],
        'confirm': ['', Validators.required]
    });         
};

userNameIsTaken(group: any, userName: string) {
    return new Promise(resolve => {

        this._accountService.read('/username/' + group.controls[userName].value)
            .subscribe(data => {
                data = data
                if (data) {
                    resolve({ taken: true })
                } else {
                    resolve(null);
                }
            });
    })
};

HTML:

<div class="input-group">
    <span class="input-group-label">Username</span>
    <input class="input-group-field" type="text" required [(ngModel)]="model.userName" ngControl="userName" #userName="ngForm">
    <control-messages control="userName"></control-messages>
    <div *ngIf="taken">Username is already in use.</div>
</div>

Answer 1

你应该这样定义你的异步验证器:

'userName': ['', ValidationService.userNameValidator, 
       ValidationService.userNameIsTaken],

而不是 Validators.compose 方法。事实上，这里是参数对应的:

'<field-name>': [ '', syncValidators, asyncValidators ]

此外，当用户名未被使用而不是`{taken: false}

时，您应该使用 null 进行解析

if (data.userName == true) {
  resolve({ taken: true })
} else {
  resolve(null);
}

有关详细信息，请参阅本文(“字段的异步验证”部分):

• http://restlet.com/blog/2016/02/17/implementing-angular2-forms-beyond-basics-part-2/

编辑

也许我的回答不够清楚。您仍然需要使用 Validators.compose，但前提是您有多个同步验证器:

this.accountForm = this._formBuilder.group({
    'firstName': ['', Validators.required],
    'lastName': ['', Validators.required],
    'userName': ['', Validators.compose([
             Validators.required,
             this.accountValidationService.userNameValidator
          ], this.userNameIsTaken],
    'email': ['', Validators.compose([
             Validators.required,
             this.accountValidationService.emailValidator
          ]],
    'password': ['', Validators.compose([
             Validators.required,
             this.accountValidationService.passwordValidator
          ]],
    'confirm': ['', Validators.required]
  });         
};

编辑1

您需要利用 ngFormControl 而不是 ngControl，因为您使用 FormBuilder 类定义控件。

<div class="input-group">
  <span class="input-group-label">Username</span>
  <input class="input-group-field" type="text" required [(ngModel)]="model.userName" [ngControl]="accountForm.controls.userName" >
  <control-messages [control]="accountForm.controls.userName"></control-messages>
  <div *ngIf="accountForm.controls.userName.errors && accountForm.controls.userName.errors.taken">Username is already in use.</div>
</div>

有关详细信息，请参阅本文:

• http://restlet.com/blog/2016/02/11/implementing-angular2-forms-beyond-basics-part-1/