用验证器包装角反应形式组件

Question

使用angular 7和Bootstrap 4，我想将Bootstrap 4输入包装在一个自定义组件中，以减少模板中的样板。

我希望最终的主要组件如下所示：

<form [formGroup]="myForm" (submit)="submit(myForm.value)">

    <app-form-control label="Lastname" placeholder="Lastname" formControlName="lastName"></app-form-control>
    <app-form-control label="Firstname" placeholder="Firstname" formControlName="firstName"></app-form-control>

    <button class="pull-right" type="submit">
        SUBMIT
    </button>
    <button (click)="reset()">
        RESET
    </button>
</form>

我的formGroup是这样创建的：

public createFormGroup() {
    return this.fb.group({
        firstName: [null, Validators.required],
        lastName: [null, Validators.required],
    });
}

app-form-control的模板应如下所示：

<div class="form-group row">
  <label class="col-2 col-form-label">{{label}}</label>
  <div class="col-10">
    <input class="form-control" placeholder="{{placeholder}}" [formControlName]="formControlName" autocomplete="nope"/>
  </div>
</div>

但是我不知道如何编写组件（使用TypeScript）。如何将外部formControlName属性绑定到内部输入字段？如何使验证工作？

Answer 1

“键”正在使用viewProvider。您使用@Input设置为formControl赋值，请参见stackblitz。“魔术”是，如果相等，则在“孩子”中引用formControl或在父对象中引用form.get（'input1'）

@Component({
  selector: 'app-form-control',
  template: `
  <div class="form-group row">
  <label class="col-2 col-form-label">{{label}}</label>
  <div class="col-10">
    <input class="form-control" placeholder="{{placeholder}}"
    [formControl]="formControl" autocomplete="nope"/>
  </div>
  </div>
  <!--you can control the properties of formControl-->
  {{formControl.valid}}{{formControl.touched}}}
`,
viewProviders: [{ provide: ControlContainer, useExisting: FormGroupDirective }]})
export class HelloComponent {

  formControl: FormControl;

  constructor(private parentF: FormGroupDirective) { }

  @Input() 
  set controlName(value) {
    this.formControl = this.parentF.form.get(value) as FormControl
  }

  @Input() label: string;
  @Input() placeholder: string;

}

并以这种方式调用组件：

<form [formGroup]="myForm" (submit)="submit(myForm.value)">
    <app-form-control label="Lastname" placeholder="Lastname" controlName="lastName"></app-form-control>
</form>