Angular-如何对FormArray中的项目重新排序? [英] Angular - How to reorder items in FormArray?

问题描述

我有一个包含一堆控件的大型表单.在此表单中，我有一组表单组，这是我的规则".

I have a large form that contains a bunch of controls. Within this form, I have an array of form groups which are my "rules".

我需要添加更改规则顺序的功能，不仅可以更改其值，还可以更改其在DOM中的视觉位置.

I need to add the ability to change the order of the rule, not only its value but its visual place in the DOM.

这是我的设置:

这些规则中的每个规则都是具有自己的表单组等的组件.它们最初显示的顺序基于其当前存储的处理顺序值.

Each one of those rules is a component that has its own form groups etc. The order they are initially displayed is based on their current stored processing order value.

在每个规则下方，我都有一个按钮来上下移动规则，这是我正在研究的内容.

Below each rule I have a button to move the rule up or down which is what I am working on.

对于反应式表单，表单组的索引是否确定其在组件UI中的位置?例如，如果我想上移一条规则，是否可以将表格组索引更改为currentIndex-1或将上面的规则更改为+1以便更改位置?

With reactive forms, does the index of a form group determine its position in the component UI? For example, if I wanted to move a rule up, could I change that form groups index to currentIndex-1 and perhaps the rule above to +1 in order to change places?

我在这里的目标是能够在UI上上下移动这些组件.由于此页面上的规则数量众多，我试图远离拖放库.

My goal here is to be able to move those components up and down on the UI. I am trying to stay away from a drag and drop library due to the amount of rules on this page.

更新:

这是我的设置中的一个小插曲:

Here is a plunker of my setup:

https://plnkr.co/edit/S77zywAa7l900F0Daedv?p=preview

推荐答案

FormArray上有几种方法，例如removeAt和insert，可以帮助您实现目标.

There are several methods on FormArray like removeAt and insert that can help you to achieve your goal.

template.html

<button class="button" (click)="move(-1, i)">Move Up</button> &nbsp; 
<button class="button" (click)="move(1, i)">Move Down</button>

component.ts

move(shift, currentIndex) {
  const rules = this.rulesForm.get('ruleData.rules') as FormArray;

  let newIndex: number = currentIndex + shift;
  if(newIndex === -1) {
    newIndex = rules.length - 1;
  } else if(newIndex == rules.length) {
    newIndex = 0;
  }

  const currentGroup = rules.at(currentIndex);
  rules.removeAt(currentIndex);
  rules.insert(newIndex, currentGroup)
}

柱塞示例

Plunker Example

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