设置属性。要求“条件”不检查任何内容

required 属性设置为元素,所需的验证工作正常。如果我设置

以下是plnkr示例: https://plnkr.co/edit/vPfmgvLxUjNyNXHtkY24 (基于 hero example documentation ).

  <form #heroForm="ngForm">  
      <div class="form-group">
        <label for="name">Required label Test</label>
        <input type="checkbox" class="form-control" [(ngModel)]="cbReqired" name="cbReqired" id="cbReqired">
      </div>

      <div [hidden]="!cbReqired">Now the Textbox should be required! (<code>required="true"</code> is set!)</div>

      <div class="form-group">
        <label for="name">Name</label>
        <input id="name" name="name" class="form-control" [attr.required]="cbReqired" [(ngModel)]="hero" #name="ngModel">

        <div *ngIf="name.invalid && (name.dirty || name.touched)" class="alert alert-danger">

          <div *ngIf="name.errors.required">
            Name is required.
          </div>
        </div>
      </div>

      <button type="submit" class="btn btn-default" [disabled]="heroForm.invalid">Submit</button>
      <button type="button" class="btn btn-default" (click)="heroForm.resetForm({})">Reset</button>
  </form>