formArray中的可拖动formGroups（反应性表单）

问题描述

在角度拖放模块中，他们为moveItemInArray（）函数提供了文档，使用此函数，我们只能在数组中拖动内容。但是，如何在formArray中改组（formGroups / formControls）？

In angular drag-drop module, they provided documentation for the moveItemInArray() function, by using this we can only drag content in an array only. but, how we could shuffle (formGroups/formControls) in formArray?

即使我尝试了moveItemInFormArray（）函数，如此处。但我无法使其正常工作。

Even I tried this moveItemInFormArray() function, as mentioned here https://github.com/angular/angular/issues/27171. but I can not make it work.

groupDrag.component.html

    <form [formGroup]="exampleForm">
      <div formArrayName="formUnits" cdkDropList (cdkDropListDropped)="drop($event)" *ngFor="let unit of exampleForm.controls.formUnits.controls; let i=index" class="rowGroup">
        <div [formGroupName]="i" class="basic-container" cdkDrag>
          <div class="row row-container" >
            <button type="button" class="drag-handle" mat-icon-button cdkDragHandle>
              <mat-icon>unfold_more</mat-icon>
            </button>

            <!-- label input field -->
            <mat-form-field  class="col-lg-4">
              <input matInput placeholder="Please enter label without spaces" formControlName="label" required>
            </mat-form-field>

            <!-- options input field -->
              <mat-form-field  class="col-lg-3">
                <input matInput placeholder="Enter Placeholdertext" formControlName="placeholder">
             </mat-form-field>

          </div>
        </div>
      </div>
    </form>

groupDrag.component.ts

drop(event: CdkDragDrop<FormGroup[]>) {
  console.log('drop event triggers')
  this.formArray = this.exampleForm.get('formUnits') as FormArray;
  const from = event.previousIndex;
  const to = event.currentIndex;
  this.moveItemInFormArray(this.formArray, from, to)
}

/**
* Moves an item in a FormArray to another position.
* @param formArray FormArray instance in which to move the item.
* @param fromIndex Starting index of the item.
* @param toIndex Index to which he item should be moved.
*/
moveItemInFormArray(formArray: FormArray, fromIndex: number, toIndex: number): void {
  const from = this.clamp(fromIndex, formArray.length - 1);
  const to = this.clamp(toIndex, formArray.length - 1);

  if (from === to) {
    return;
  }

  const delta = from > to ? 1 : -1;
  for (let i = from; i * delta < to * delta; i += delta) {
    const previous = formArray.at(i);
    const current = formArray.at(i + delta);
    formArray.setControl(i, current);
    formArray.setControl(i + delta, previous);
  }
}

/** Clamps a number between zero and a maximum. */
clamp(value: number, max: number): number {
  return Math.max(0, Math.min(max, value));
}

推荐答案

以下是工作示例：

groupDrag.component.ts

import {moveItemInFormArray} from "./move-item-in-form-array";

drop(event: CdkDragDrop<string[]>) {
    moveItemInFormArray(this.arrayControls, event.previousIndex, event.currentIndex);
}

move-item-in-form-array.ts

import {FormArray} from '@angular/forms';

/**
 * Moves an item in a FormArray to another position.
 * @param formArray FormArray instance in which to move the item.
 * @param fromIndex Starting index of the item.
 * @param toIndex Index to which he item should be moved.
 */
export function moveItemInFormArray(formArray: FormArray, fromIndex: number, toIndex: number): void {
  const dir = toIndex > fromIndex ? 1 : -1;

  const from = fromIndex;
  const to = toIndex;

  const temp = formArray.at(from);
  for (let i = from; i * dir < to * dir; i = i + dir) {
    const current = formArray.at(i + dir);
    formArray.setControl(i, current);
  }
  formArray.setControl(to, temp);
}

这篇关于formArray中的可拖动formGroups（反应性表单）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！