Question

在Angular 6应用程序的注册表格中，我有一个复选框已被选中。我需要检查用户是否已取消选中该复选框，是否已选中，所以我想显示一条错误消息。

这是我在.html文件中的复选框，

 <div class="form-group">
       <div class="round">
            <input
                  type="checkbox"
                  id="checkbox33"
                  formControlName="agree">
             <label for="checkbox33"></label>
        </div>
        <small class="text-muted">Agree to our <a href="#" class="link">Terms
                  Of Use</a> and <a href="#" class="link">Privacy Policy</a>.
                </small>
        <span *ngIf="!worldWideRegisterForm.get('agree').valid" class="text-danger">You should agree!</span>

  </div>

这是.ts文件中的ngOnInit（）

ngOnInit() {
    this.worldWideRegisterForm = new FormGroup({
      'userName': new FormGroup({
        firstName: new FormControl(null, Validators.required),
        lastName: new FormControl(null, Validators.required)
      }),
      'email': new FormControl(null, [Validators.required, Validators.email]),
      'phone': new FormControl(null, Validators.required),
      'address': new FormGroup({
        line1: new FormControl(null, Validators.required),
        line2: new FormControl(null),
      }),
      'area': new FormGroup({
        'province': new FormControl(null, Validators.required),
        'city': new FormControl(null, Validators.required),
        'postalCode': new FormControl(null, Validators.required),
      }),
      'password': new FormControl(null, [Validators.required, Validators.minLength(6)]),
      'agree': new FormControl(true, Validators.required)
    });
  }

Answer 1

使用角度验证器requiredTrue

'agree': new FormControl(true, Validators.requiredTrue)

错误

<div *ngIf="myTrue.hasError('required')">
   Agree the T&C    
</div>

官方链接https://angular.io/api/forms/Validators#requiredTrue

Answer 2

代替false 与'agree': new FormControl(true, Validators.required)一起尝试。

Answer 3

我可以通过编写复选框的自定义验证来解决我的问题，并获得确切的输出作为其他答案。我也想分享我的答案。

这是我的复选框的.html，

<div class="form-group">
        <div class="round">
             <input
                  type="checkbox"
                  id="checkbox33"
                  formControlName="agree">
             <label for="checkbox33"></label>
         </div>
         <small class="text-muted">Agree to our <a href="#" class="link">Terms
                Of Use</a> and <a href="#" class="link">Privacy Policy</a>.
              </small>
         <span *ngIf="!worldWideRegisterForm.get('agree').valid" class="text-danger">
           <span *ngIf="worldWideRegisterForm.get('agree').errors['checkBoxIsForbidden']">Agree to our terms & conditions.</span>
              </span>
  </div>

这就是我添加到.ts文件中的内容

'agree': new FormControl(true, [Validators.required, this.forbiddenCheckBox])

//fuction to check the checkbox
 forbiddenCheckBox(control: FormControl): { [s: string]: boolean } {
    if (control.value === false) {
      return {'checkBoxIsForbidden': true};
    }
  }

如果未选中复选框，则设置复选框验证

3 个答案: