Angular 2表单“无法找到路径控制”

Cannot find control with path: ‘list_items -> list_item’

我的组件：

@Component({
  selector: 'app-list',templateUrl: './list.component.html',styleUrls: ['./list.component.css']
})
export class ListComponent implements OnInit {

  listForm: FormGroup;

  constructor(private nodeService: NodeService,private messageService: MessageService,private fb: FormBuilder,private listService: ListService) { 
    this.listForm = this.fb.group({
      title: ['',[Validators.required,Validators.minLength(5)]],list_items: this.fb.array([
        this.initListItem(),])
    });
  }


  initListItem() {
    return this.fb.group({
      list_item: ['']
    });
  }
  initListItemType() {
    return this.fb.group({
      list_item_type: ['']
    });
  }

  addListItem() {
    const control = <FormArray>this.listForm.controls['list_items'];
    control.push(this.initListItem());
  }

模板(list.component.html)：

<h2>Add List </h2>

<form [formGroup]="listForm" novalidate (ngSubmit)="addList(listForm)">
  <div class="form-group">
    <input type="text" class="form-control" formControlName="title" placeholder="Title">
  </div>

  <div formArrayName="list_items">
    <div *ngFor="let list_item of listForm.controls.list_items.controls; let i=index" class="panel panel-default">
      {{i + 1}}.) <input type="text" formControlName="list_item" placeholder="List Item" class="form-control">
    </div>
    <a (click)="addListItem()">Add List Item +</a>

  </div>

  <button type="submit">Submit</button>
</form>

标题工作正常,但我找不到我对“formControlName”的错误,这导致错误.

在此问题上提前感谢您的任何帮助.

更新我改变的内容
list.component.html

<h2>Add List </h2>

<form [formGroup]="listForm" novalidate (ngSubmit)="addList(listForm)">
  <div class="form-group">
    <input type="text" class="form-control" formControlName="title" placeholder="Title">
  </div>

  <div formArrayName="list_items">
    <div *ngFor="let list_item of listForm.controls.list_items.controls; let i=index" class="panel panel-default">
      {{i + 1}}.) <input type="text" formControlName="{{i}}" placeholder="List Item" class="form-control">
    </div>
    <a (click)="addListItem()">Add List Item +</a>

  </div>

  <button type="submit">Submit</button>
</form>

在我的组件中,我更改了构造函数和我的addListItem方法：

listForm: FormGroup;

  constructor(private nodeService: NodeService,list_items: this.fb.array([
          [''],])
    });
  }

  addListItem() {
    const control = <FormArray>this.listForm.controls['list_items'];
    control.push(this.fb.control(['']));
    console.log(control)
  }