How to avoid same value repeating in the formcontrolname using angular8

问题

i have used formArray to loop the values and on selection of one item, we can move right and left based on which side we have selected.Here, i am selecting last item from right and moving to left, then i select last but one and move that to left. Then the duplicate value has come. I think it is due to index value mismatch. I am not able to rectify this issue. can anyone help me out to solve this.

DEMO: Working Demo

HTML:

<div class="card-body overflow-auto py-0" formArrayName="agentNotGroupView">
                  <div class="swap-list-item" *ngFor="let items of agentNotinView; let i = index" [formGroupName]="i"
                    [class.selected]="selected2.includes(items)">
                    <input formControlName="agentNotInViewValue" [readOnly]="true" (click)="onSelect(2, items)" [disabled] = "isReadOnly"/>
                  </div>
                </div>

TS:

    this.agentNotInViewArray = this.FB.array(
            this.agentNotinView.map(x => this.FB.group({
              agentNotInViewValue: this.FB.control(x.value)
            }))
          );

          this.agentGroupNotViewInfoForm = this.FB.group({
            agentNotGroupView: this.agentNotInViewArray
          })

move from one button to other:
moveFrom(fromListNumber: number) {
    const selected: MyInterface[] = this.getSelected(fromListNumber);
    if (selected.length === 0) {
      return;
    }

    const toListNumber: number = fromListNumber === 1 ? 2 : 1;

    const fromModel: MyInterface[] = this.getModel(fromListNumber);
    const fromFormArray: FormArray = this.getFormArray(fromListNumber);

    const toModel: MyInterface[] = this.getModel(toListNumber);
    const toFormArray: FormArray = this.getFormArray(toListNumber);

    // remove items and form groups    
    selected.forEach((item) => {
      const index: number = fromModel.indexOf(item);
      const formGroup: FormGroup = fromFormArray.controls[index] as FormGroup;

      // remove from model
      fromModel.splice(index, 1);
      // remove from from array
      fromFormArray.removeAt(index);

      // add to form array
      toFormArray.push(formGroup);
      // add item to model
      toModel.push(item);
    });
    // clear selected
    selected.length = 0;
  this.groupInfoForm();
  this.notGroupInfoForm();
    }

As per my debug, items.value and items.id comes fine, but formcontrolName gives the duplicate value. help needed to rectify this.

回答1:

I was able to solve this by adding an if ans else condition while calling the form again, so it was.

TS:

moveFrom(fromListNumber: number) {
    const selected: MyInterface[] = this.getSelected(fromListNumber);
    if (selected.length === 0) {
      return;
    }

    const toListNumber: number = fromListNumber === 1 ? 2 : 1;

    const fromModel: MyInterface[] = this.getModel(fromListNumber);
    const fromFormArray: FormArray = this.getFormArray(fromListNumber);

    const toModel: MyInterface[] = this.getModel(toListNumber);
    const toFormArray: FormArray = this.getFormArray(toListNumber);

    // remove items and form groups    
    selected.forEach((item) => {
      const index: number = fromModel.indexOf(item);
      const formGroup: FormGroup = fromFormArray.controls[index] as FormGroup;

      // remove from model
      fromModel.splice(index, 1);
      // remove from from array
      fromFormArray.removeAt(index);

      // add to form array
      toFormArray.push(formGroup);
      // add item to model
      toModel.push(item);
    });
    // clear selected
    selected.length = 0;
    if(fromListNumber == 2) {
  this.groupInfoForm();
    } else if(fromListNumber == 1) {
  this.notGroupInfoForm();
    }
    }

来源：https://stackoverflow.com/questions/60963991/how-to-avoid-same-value-repeating-in-the-formcontrolname-using-angular8