Question

我正在尝试定义一个包含动态表单的组件（使用ReactiveForms），用户应该能够添加/删除控件。控件可以采用多种形式，并且必须在Component之外定义，因此我认为TemplateRef最适合于此。

我正在努力找到一种方法将外部定义的Control绑定到内部Form，通过使用formControlName

以下是实施的开始：

fgets

-

// expandable.component.ts

[...]
@Component({
  selector: 'expandable',
  templateUrl: 'app/component/common/expandable/expandable.component.html',
  styleUrls: ['app/component/common/expandable/expandable.component.css']
})
export class ExpandableComponent {
  @ContentChild('childTemplate') childTemplate: TemplateRef<any>;

  @Input() children: Array<any>;
  public form: FormGroup;

  constructor(private _changeDetector: ChangeDetectorRef,
              private _formBuilder: FormBuilder) {
    this.children = [];
  }

  public ngOnInit(): void {
    this.form = this._formBuilder.group({
      children: this._formBuilder.array([])
    });

    const arrayControl = <FormArray>this.form.controls['children'];
    this.children.forEach(child => {
      const group = this.initChildForm();
      arrayControl.push(group);
    });
  }

  private initChildForm(): AbstractControl {
    return this._formBuilder.group({
      key: ['Initial Key', [Validators.required]],
      value: ['Initial Value', [Validators.required]]
    });
  }

  public addChild(): void {
    const control = <FormArray>this.form.controls['children'];
    control.push(this.initChildForm());
    this._changeDetector.detectChanges();
  }
}

尝试在外部定义模板：

<!-- expandable.component.html -->

<form [formGroup]="form">
  <div class="form-group">
    <div formArrayName="children">
      <div *ngFor="let child of form.controls.children.controls; let i=index">
        <div [formGroupName]="i">
          <template 
             [ngTemplateOutlet]="childTemplate" 
             [ngOutletContext]="{ $implicit: child }"></template>
        </div>
      </div>
    </div>
  </div>
  <a (click)="addChild()">Add Child</a>
</form>

我天真地尝试将formControlName绑定到来自outter的隐式传递的上下文，但没有运气，因为我得到“找不到名字的控件：'value'”。理想情况下，我希望能够将formControlName绑定到<expandable> <template #childTemplate> <input class="form-control" formControlName="value" /> </template> </expandable>，但我也看不到这样做。

对此有何想法？

Answer 1

是的，这是可能的：

您需要实现ControlValueAccessor和ngModel注入的formControlName接口，如下所示：

@Directive({
  selector: 'control',
  providers: [
    {provide: NG_VALUE_ACCESSOR, multi: true, useExisting: SwitchControlComponent}
  ]
})
export class SwitchControlComponent implements ControlValueAccessor {
  isOn: boolean;
  _onChange: (value: any) => void;

  writeValue(value: any) {
    this.isOn = !!value;
  }

  registerOnChange(fn: (value: any) => void) {
    this._onChange = fn;
  }

  registerOnTouched() {}

  toggle(isOn: boolean) {
    this.isOn = isOn;
    this._onChange(isOn);
  }
}

html：

  <expandable>
    <template #childTemplate>
      <div [formGroup]="form">
         <input control class="form-control" 
           formControlName="value" />
         </template>
      </div>
  </expandable>

进一步阅读：

With new forms api, can't add inputs from child components without adding additional form tags

Angular2：将表单上下文绑定到ngTemplateOutlet

1 个答案: