Angular FormArray 的用法

要注意的几点:

    this.groupForm = this.fb.group({
      Arr: this.fb.array([]) // formarray
    });

// formarray表单
    this.groupForm = this.fb.group({
      Arr: this.fb.array([this.createForm()]) // formarray
    });
private createForm() {
  return  this.fb.group({
          control1:  ['', Validators.required],
          control2:  ['', Validators.required],
              Name:  ['', Validators.required],
              Code:  ['', Validators.required],
             Level:  ['', Validators.required],
            Remark:  [''],
        });
}

// 增加表单
  newForm() {
    const arr = this.groupForm.get('Arr') as FormArray;
    arr.push(this.createForm()); // 推送form新表单
  }

// 移除表单
  removeForm(i: number) {
    const arr = this.groupForm.get('Arr') as FormArray;
    arr.removeAt(i); // 根据索引移除对应的表单
  }

<form [formGroup]="groupForm" id="detail" class="am-g">

    <p formArrayName="Arr">
        <p *ngFor="let form of ArrForm.controls; let i=index;" [formGroupName]="i">
        <input type="text" formControlName="Name">
        ...............

        <!-- 增加移除表单 -->
        <button (click)="newForm()">增加表单</button>
        <button (click)="removeForm(i)">增加表单</button>
    </p>

问题:

另外, 我还有个问题没有搞明白, 为什么前台页面 formArrayName里面 必须要加上 [formGroupName]=”i”. 不然就会报错.