Angular 在父组件嵌套表单中使用子组件表单 [英] Angular Use Child Component Form in Parent Component Nested Form

问题描述

将子组件表单放入父组件表单的最佳方法是什么?我们使用的是 2019 年最新的 Angular 8.经过研究，以下方法不能完全奏效.

父组件:

 ngOnInit() {this.parentForm = this.fb.group({childForm1:等})

子组件:

this.ChildForm = this.formBuilder.group({'streetNumber': [null, [Validators.required, Validators.maxLength(32)]],'streetType': [null, [Validators.maxLength(8)]],'city': [null, [Validators.maxLength(32)]],'state': [null, [Validators.maxLength(16)]],'postalCode': [null, [Validators.maxLength(16)]],}, { 验证器:atLeastOneLocationRequired })

}

方法一:

这个方法，https://itnext.io/partial-reactive-form-with-angular-components-443ca06d8419经过严格的测试表明 ParentForm 有效，即使 Child Form 无效.这不应该发生.

ngOnInit() {this.parent = this.fb.group({全名:空})

}

formInitialized(name: string, form: FormGroup) {this.checkoutForm.setControl(name, form);}

方法二:

方法 2 使用 ViewChild，这是听力不好的做法.https://davembush.github.io/attaching-an-angular-child-component-s-form-to-a-parent/

@ViewChild(ChildComponent) childComponent: ChildComponent;现在在 ngAfterViewInit() 中，我们可以将孩子的 FormGroup 添加为附加的控件"，并将父 FormGroup 设置为父控件的 FormGroup.ngAfterViewInit() {this.form.addControl('childForm', this.childComponent.form);this.childComponent.form.setParent(this.form);}

那么 Angular 8 中最好的 Angular 官方实践是什么?

解决方案

我已经根据你的问题创建了小场景.

父组件:

HTML:

<app-child [form]="form"></app-child><pre>{{form.value |json}}</pre></表单>

TS:

import { Component, OnInit } from '@angular/core';从@angular/forms"导入 { FormGroup, FormBuilder, Validators };@成分({选择器:'我的应用'，templateUrl: './app.component.html',styleUrls: ['./app.component.css']})导出类 AppComponent 实现 OnInit {表格:表格组；构造函数(私有 fb:FormBuilder){}ngOnInit() {this.form = this.fb.group({childForm1: '',streetNumber: [null, [Validators.required, Validators.maxLength(32)]],streetType: [null, [Validators.maxLength(8)]],城市:[null，[Validators.maxLength(32)]]，状态:[null，[Validators.maxLength(16)]]，postalCode: [null, [Validators.maxLength(16)]],})}}

子组件:

HTML:

<input formControlName="streetNumber"><br><input formControlName="streetType"><br><input formControlName="city"><br><input formControlName="state"><br><input formControlName="postalCode">

TS:

import { Component, OnInit, Input } from '@angular/core';从@angular/forms"导入{FormGroup}；@成分({选择器:'app-child'，templateUrl: './child.component.html',styleUrls: ['./child.component.css']})导出类 ChildComponent 实现 OnInit {@Input() 表单:FormGroup；构造函数(){}ngOnInit() {}}

工作链接:https://stackblitz.com/edit/angular-gjrphg

更新了多个孩子的链接:https://stackblitz.com/edit/angular-svnqfh?file=src/app/app.component.html

Whats the best way to place a ChildComponent form into a Parent Component Form? We are using the latest Angular 8 in 2019. The following methods below after research do not work fully.

Parent Component:

 ngOnInit() {
    this.parentForm = this.fb.group({
       childForm1: etc
    })

Child Component:

this.ChildForm = this.formBuilder.group({
  'streetNumber': [null, [Validators.required, Validators.maxLength(32)]],
  'streetType': [null, [Validators.maxLength(8)]],
  'city': [null, [Validators.maxLength(32)]],
  'state': [null, [Validators.maxLength(16)]],
  'postalCode': [null, [Validators.maxLength(16)]],
}, { validator: atLeastOneLocationRequired })

}

Method 1:

This method, https://itnext.io/partial-reactive-form-with-angular-components-443ca06d8419 after rigorous testing states ParentForm is Valid, even if the Child Form is invalid. This should not occur.

ngOnInit() {
  this.parent = this.fb.group({
    fullName: null
  })

}

formInitialized(name: string, form: FormGroup) {
  this.checkoutForm.setControl(name, form);
}

Method 2:

Method 2 utilizes ViewChild, which are hearing is bad practice. https://davembush.github.io/attaching-an-angular-child-component-s-form-to-a-parent/

@ViewChild(ChildComponent) childComponent: ChildComponent;

And now in ngAfterViewInit() we can add the child’s FormGroup as an additional "control" and set the parent FormGroup to the parent control’s FormGroup.

ngAfterViewInit() {
  this.form.addControl('childForm', this.childComponent.form);
  this.childComponent.form.setParent(this.form);
}

So what is best Angular official practice in Angular 8?

解决方案

I've create small scenario according to your problem.

parentComponent:

HTML:

<form [formGroup]="form">
  <app-child [form]="form"></app-child>
  <pre>{{form.value | json}}</pre>
</form>

TS:

import { Component, OnInit } from '@angular/core';
import { FormGroup, FormBuilder, Validators } from '@angular/forms';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent implements OnInit {
  form: FormGroup;
  constructor (private fb: FormBuilder) {}

   ngOnInit() {
    this.form = this.fb.group({
      childForm1: '',
      streetNumber: [null, [Validators.required, Validators.maxLength(32)]],
      streetType: [null, [Validators.maxLength(8)]],
      city: [null, [Validators.maxLength(32)]],
      state: [null, [Validators.maxLength(16)]],
      postalCode: [null, [Validators.maxLength(16)]],
    })
  }
}

childComponent:

HTML:

<div [formGroup]="form">
  <input formControlName="streetNumber"><br>
  <input formControlName="streetType"><br>
  <input formControlName="city"><br>
  <input formControlName="state"><br>
  <input formControlName="postalCode">
</div>

TS:

import { Component, OnInit, Input } from '@angular/core';
import { FormGroup } from '@angular/forms';

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.css']
})
export class ChildComponent implements OnInit {
   @Input() form: FormGroup;
  constructor() { }

  ngOnInit() {
  }

}

Working link: https://stackblitz.com/edit/angular-gjrphg

Updated link for multiple child: https://stackblitz.com/edit/angular-svnqfh?file=src/app/app.component.html

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