角度 4 中的响应式表单在单击按钮时提交复选框值数组

Question

我正在开发一个在 Angular 4 中的应用程序。我正在使用反应式表单。我正在构建一个简单的提交表单，如下所示：

<form [formGroup]="newPostForm" novalidate>
      <input formControlName="Title" type="text" class="form-control" id="txtTitle" placeholder="Enter title of post..."> 
        <h4>Categories</h4>
        <ul>
          <li *ngFor="let cat of catsList">
            <span style="margin-top: -2.5px;">
              <input id="CheckBox" type="checkbox" formNameArray="Categories" [value]='cat.CategoryID' checked='false'></span> {{cat.CategoryName}}
          </li>
        </ul>
    <input type="submit" name="btnSubmit" value="Save" id="btnSubmit" (click)="onSubmitedForm()" class="btn btn-primary">
</form>

下面是new-post.component.ts文件：

export class NewPostComponent implements OnInit {
  public catsList: any = [];
  public newPostDTO: any = [];
  newPostForm: FormGroup;
  constructor(private _postsSvc: PostsService,
    private _categoriesSvc: CategoriesService,
    private _formGroup: FormBuilder) { }
  ngOnInit() {
    this.getAllCategories();
    this.initProperties(); //init all props
    this.createPostForm(); 
  }

  initProperties() {
    this.newPostDTO = {
      Title: null,
      Content: null,
      Categories: null
    };
  }
  createPostForm() {
    this.newPostForm = this._formGroup.group({
      Title: [''],
      Categories: new FormArray([])
    });
  }
  onSubmitedForm() {
    console.log(this.newPostForm.value.Categories);
    this.newPostDTO = {
      Title: this.newPostForm.value.Title,
      Categories:  this.newPostForm.value.Categories,
    };
    this._postsSvc.addPost(this.newPostDTO).subscribe(data => {
      if (data.status === 201) {
      }
    });
  }

getAllCategories() {
  this._categoriesSvc.getCategories().subscribe(
    data => this.catsList = data.body );
  }

}我想在单击提交按钮时将选中类别的所有 ID 作为数组获取。我怎样才能做到这一点？我试过了，但在我单击提交按钮后类别数组的值为空。

谢谢大家！

Answer 1

控件的反应式表单源是类而不是模板，因此如果要创建动态复选框，则需要创建多个表单控件

如果您希望仅在提交后

进行更改，则可以传递{updateOn："submit"}以仅在提交后获取数据

catsList = [{cName:"cat1"},{cName:"cat2"},{cName:"cat3"}];
  newPostForm: FormGroup;
  constructor(private fb: FormBuilder) {
    const control = this.catsList.map((d)=>new FormControl())
    this.newPostForm = this.fb.group({
      Title: [''],
      Categories: new FormArray(control,{updateOn:"submit"})
    })
  }
  get catControl() {
    return this.newPostForm.get('Categories')['controls'];
  }
  onSubmitedForm() {
  }

FormArray 基于索引，因此我们应该将索引用于单个 formControl

<form [formGroup]="newPostForm" > 
    <input formControlName="Title" type="text" class="form-control" id="txtTitle" placeholder="Enter title of post..."> 
        <h4>Categories</h4>
        <ul>
          <li *ngFor="let cat of catControl;let i =index">
            <span style="margin-top: -2.5px;" formArrayName="Categories">
              <input  [formControlName]="i" id="CheckBox" type="checkbox"  ></span> {{catsList[i].cName}}
          </li>
        </ul>
    <input type="submit" name="btnSubmit" value="Save" id="btnSubmit" (click)="onSubmitedForm()" class="btn btn-primary">
</form>

例如：https：//stackblitz.com/edit/angular-dzxcf1