检查Angular2表单是否在组件内有效

Question

我试图检查表单是否有效,以防止进一步执行,如果不是.

这是我的表格:

<form (ngSubmit)="updateFirstName(firstNameForm)" #firstNameForm="ngForm" novalidate>
    <div class="form-group" ng-class="getCssClasses(formCtrl, formCtrl.firstName)">
        <div class="input-group">
            <input type="text"
                   ngControl="firstName"
                   #firstName="ngForm"
                   required
                   minlength="2"
                   maxlength="35"
                   pattern_="FIRST_NAME_PATTERN"
                   [ngModel]="currentUserAccount?.firstName"
                   (ngModelChange)="currentUserAccount ? currentUserAccount.firstName = $event : null"
                   placeholder="{{'FIRST_NAME_FORM.NEW_FIRST_NAME'| translate }}"
                   class="form-control"/>
        </div>

        <div [hidden]="firstName.valid">
            <div *ngIf="firstName?.errors?.minlength" class="control-label">{{'FIRST_NAME_FORM.MIN_LENGTH'| translate}}</div>
        </div>
    </div>
    <div class="form-group">
        <button type="submit" class="btn btn-primary pull-right" [disabled]="buttonDisabled">{{'FIRST_NAME_FORM.SUBMIT'| translate}}</button>
        <a [routerLink]="['/dashboard/useraccount']" class="btn btn-link pull-right text-right">{{'FORM_CANCEL' | translate}}</a>
    </div>
</form>

但是,当我提交无效表单时,我在控制台中注意到有效属性NgForm是true...

 updateFirstName(firstNameForm) {
   console.log(firstNameForm);//the valid attribute of firstNameForm is true...
 }

任何人都可以让我知道为什么会这样吗？

Answer 1

你正在做模板驱动的表格.请参考这个简单的插件

<h1>Employee Form</h1>
<form #personForm="ngForm" (submit)="personFormSubmit(personForm)" novalidate>
    <div>
        <div>
            <input id="nameInput" type="text" name="name"
                   ngControl="name"
                   required
                   minlength="2"
                   maxlength="35"
                   [(ngModel)]="person.name" />
        </div>
    </div> 
    <div>
      <button type="submit">Submit</button>
    </div>
    <div style="color: red">{{validationMessage}}</div>
</form>

然后是控制器:

import { Component } from '@angular/core';
import { FORM_DIRECTIVES, ControlGroup, Control, Validators, FormBuilder, Validator, } from '@angular/common';
import 'rxjs/Rx';

export class Person {
    id: number;
    name: string;
}

@Component({
    selector: 'my-app',
    directives: [FORM_DIRECTIVES],
    templateUrl: 'app/app.component.html'
})
export class AppComponent {

    person: Person;
    validationMessage: string;

    constructor() {
        this.person = new Person();
        this.validationMessage = "";
    }

    personFormSubmit(personForm: ControlGroup) {
        if (personForm.valid) {
          this.validationMessage = "Form Is Valid";
        }
        else
        {
          this.validationMessage = "Form Is Not Valid";
        }
    }

}

如果您想转向更复杂的动态验证,那么转换为模型驱动的表单会更好.就像这个插件一样

Answer 2

这是预期的行为

我在更改日志中找到了2.0.0-alpha.46(2015-11-11)

以前,ControlGroup和ControlArray的controlsErrors getter返回了直接子节点的错误.这很令人困惑,因为结果不包括嵌套子节点的错误(ControlGroup - > ControlGroup - > Control).使controlsErrors包含此类错误需要发明一些自定义序列化格式,应用程序必须理解这些格式.由于controlsErrors只是一种方便的方法,并且它引起了混乱,我们正在删除它.如果要将整个表单的错误序列化为单个对象,可以手动遍历表单并累积错误.这样,您可以更好地控制错误的序列化方式.

那么对于文档ControlGroup和ControlArray应更新

另见https://github.com/angular/angular/issues/6504#issuecomment-171950667

您可以检查是否firstNameForm.valid是false再重复错误对照组和控制.

本NgForm类具有errors属性,因为它继承AbstractControlDirective但是从嵌套控件的错误不会收集在那里.