用验证器包装角反应形式组件 [英] Wrapping angular reactive form component with validator

问题描述

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.

Working with angular 7 and Bootstrap 4, I want to wrap my bootstrap 4 inputs in a custom component in order to reduce the boilerplate in my templates.

我希望最终的主要组件看起来像这样:

I want that the final main component look like:

<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:

Where my formGroup is created like this:

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

app-form-control模板应如下所示:

The template of app-form-control should look like this:

<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(在TypeScript中).如何将外部formControlName属性绑定到内部输入字段?如何进行验证?

But I don't know how to write the component (in TypeScript). How do I bind the outer formControlName attribute to the inner input field? How to make validation work?

推荐答案

键"正在使用viewProvider.您使用@Input设置为formControl赋值，请参见

The "key" is using viewProvider. You use a @Input set to give value to a formControl, see stackblitz. The "magic" is that if equal refered to formControl in the "children" or form.get('input1') in the parent

@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:

And call the component this way:

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

更新好吧，(一年后)请考虑一下堆栈闪电错误.当您(单击)按钮时，创建一个新表单:

Update well, (after a year) take account the stackblitz was erroneous. when you (click) in buttons create a new Form:

 this.form=this.createForm({note:'lll'})

此中断"了组件和表单之间的关系，因为该关系是关于旧表单的-仅在更改@Input"nameControl"时才更改.因此，正确的方法是使用setValue为表单赋予新值.

This "break" the relationship between the component and the form because the relation is about the older form -only change if change the @Input "nameControl". So the correct is use a setValue to give a new value to the form.

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