如何在Angular Reactive Formarray中使级联下拉列表工作而不会弄乱下拉值

Question

在第4张图片、第5张图片和第6张图片上，您可以看到添加选项按钮起作用，但当我在选项2第一个下拉列表中选择一个标准时，它与选项1第二个下拉列表搞砸了，现在它还包含了第二个选项的下拉列表选项

这是我的html代码

<form [formGroup] = "profileForm">

  <h1>Profile Form</h1>

 <div>
  <label for = "first-name-input">First Name</label>
  <input type="text" id="first-name-input" formControlName ="firstNameInput">
</div>
 <div>
    <label for = "last-name-input">Last Name</label>
    <input type="text" id="last-name-input" formControlName ="lastNameInput">
  </div>

  <div formArrayName="optionGroups">

    <div *ngFor="let optionGroup of profileForm.controls['optionGroups'].controls;  let i=index "[formGroup]="optionGroup">


      <h4>Option {{ i + 1 }} </h4>




     <div>
      <label for = "select-input">Criteria</label>
      <select id="select-input" (change)="onSelectSelect($event.target.value, i)"  formControlName ="selectInput">

          <option value="0" disabled selected>Select a Criteria</option>
          <option *ngFor="let select of selects"  [value]= "select.name">{{select.id}}</option>


        </select>

        <label for = "where-input">Option</label>
        <select id="where-input" formControlName ="whereInput">
  
            <option value="0" disabled selected>Select a Option</option>
            <option *ngFor="let where of wheres" value= {{where.name}}>{{where.id}}</option>


          </select>

          <button type ="button" (click)="removeOptionGroup(i)">X</button>

         


     </div>

    </div>

   </div>
   <button type ="button" (click)="addOptionGroup()">Add Options</button>
   <div>

    <button type ="button" (click)="saveProfileForm()">Send </button>

   

   </div>

</form>

这是我的组件文件

export class PowComponent {

 selects: Select[];
 wheres: Where[];


 public profileForm : FormGroup;

 public addOptionGroup(){

 const fa = this.profileForm.controls["optionGroups"] as FormArray;

  fa.push(this.newOptionGroup());

  }

  public removeOptionGroup(index: number){

   const fa = this.profileForm.controls["optionGroups"] as FormArray;

    fa.removeAt(index);

   }


   public saveProfileForm(){

    console.log(this.profileForm.value);
   }



   constructor(public router: Router,  public dropdownqueryservice:    DropDownQueryService , private fb : FormBuilder) {
    this.profileForm = this.fb.group({

        firstNameInput : [ "" ],
        lastNameInput : [ "" ],
        optionGroups : this.fb.array([
            this.fb.group({

              selectInput : [ "" ],
              whereInput : [ "" ],

          }),
       ]),
    });

    this.selects = this.dropdownqueryservice.getSelect();
    this.wheres=[];

}

onSelectSelect(selectid, i) {
    this.wheres = this.dropdownqueryservice.getWhere().filter((item)=> item.selectid == selectid);

  }


 private newOptionGroup() {
  return new FormGroup({

      selectInput: new FormControl(""),
      whereInput: new FormControl(""),

  });
   }

  }

Answer 1

正如我之前在评论中提到的，问题来自多个选择表单的唯一selects数组。

您必须创建Select的数组数组，其中包含每个选择值的可能条件数组。

这里有一个stackblitz解决方案建议，我做了一些修改以保持简单并使其工作。如果您想更明确地表达您的担忧，请随意进行分叉和编辑。