推入数组时

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推入数组时，ngFor 和 ngModel 重置输入

本文介绍了推入数组时，ngFor 和 ngModel 重置输入的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在尝试创建一个表单，您可以在其中添加多行，然后再发送.为此，我将数据存储在 Lines 数组中，并使用 ngFor 和 ngModel 将数据绑定/检索到我的表单中.

这是我的代码的样子

导出类 MyComponent 实现 OnInit {行:行[] = [];构造函数(){}ngOnInit() {this.lines.push(new Line("XXXXXX1",0,0));}添加行(){让 line = (new Line("XXXXXX1",0,0));this.lines.push(line);}节省(){控制台日志(this.lines)；}}类行{类型:字符串；qteRejet : 数量；qteComm:数字；构造函数(类型:字符串 =XXXX1"，qteRej:数字 = 0，qteComm:数字 = 0){this.type = 类型；this.qteRejet = qteRej;this.qteComm = qteComm;}}

和形式:

 
<div class="row" *ngFor="let line of lines; let ind=index;"><div class="col-lg-1"><i class="fa fa-2x fa-plus-square add-btn" (click)="addLine()" *ngIf="lines[lines.length-1] === line"></我＞
<div class="col-lg-3"><select class="form-control" name="type" [(ngModel)]="lines[ind].type"><option>XXXXXX1</option><option>XXXXXX2</option><option>XXXXXX3</option></选择>

<div class="col-lg-4"><input class="form-control" type="number" min="0" name="qteCommande" [(ngModel)]="lines[ind].qteComm">

<div class="col-lg-4"><input class="form-control" type="number" min="0" name="qteRejet" [(ngModel)]="lines[ind].qteRejet">

当我一次添加所有行时，表单完美运行.现在，当我尝试填充一行然后添加另一行时，出于某种原因，表单会重置之前输入的行.

但是当我检查我的数组时，它仍然有输入的值

有人可以解释这里发生了什么/我做错了什么吗?任何帮助将不胜感激.

我尝试按照 @Ploppy 的建议使用 trackBy 并在我的行中添加了一个 id.我还在表单中添加了这一行:

{{line.id}} |{{line.type}} |{{line.qteComm}} |{{line.qteRejet}}</p>

这就是正在发生的事情:

表单已重置，但值已正确绑定.

解决方案

所以我终于在我的代码中找出了问题所在.我的输入在 form 中，添加一个新行添加了一个具有相同 name 的输入(这在 Agular 2 中是不允许的).用 name=attribute-{{id}} 替换我的 name 属性解决了问题.

<div class="row" *ngFor="let line of lines; let ind=index;"><div class="col-lg-1"><i class="fa fa-2x fa-plus-square add-btn" (click)="addLine()" *ngIf="lines[lines.length-1] === line"></我＞
<div class="col-lg-3"><select class="form-control" name="type-{{ind}}" [(ngModel)]="lines[ind].type"><option>XXXXXX1</option><option>XXXXXX2</option><option>XXXXXX3</option></选择>

<div class="col-lg-4"><input class="form-control" type="number" min="0" name="qteCommande-{{ind}}" [(ngModel)]="lines[ind].qteComm">

<div class="col-lg-4"><input class="form-control" type="number" min="0" name="qteRejet-{{ind}}" [(ngModel)]="lines[ind].qteRejet">

这是一个总结一切的Plunker:Plunker

I'm trying to create a form where you can add multiple lines before sending it. For that I'm using storing data in an array of Lines and use ngFor and ngModel to bind / retrieve data into my form.

Here is what my code looks like

export class MyComponent implements OnInit {
  lines : Line[] = [];

  constructor() { }

  ngOnInit() {
    this.lines.push(new Line("XXXXXX1",0,0));
  }

  addLine(){
    let line = (new Line("XXXXXX1",0,0));
    this.lines.push(line);
  }

  save(){
    console.log(this.lines);
  }
}

class Line {
  type: string;
  qteRejet : number;
  qteComm : number;

  constructor(type: string = "XXXX1", qteRej: number = 0, qteComm : number = 0){
    this.type = type;
    this.qteRejet = qteRej;
    this.qteComm = qteComm;
  }
}

and the form :

      <div class="form-group">
          <div class="row" *ngFor="let line of lines; let ind=index;">
            <div class="col-lg-1">
              <i class="fa fa-2x fa-plus-square add-btn" (click)="addLine()" *ngIf="lines[lines.length-1] === line"></i>
            </div>
            <div class="col-lg-3">
              <select class="form-control" name="type" [(ngModel)]="lines[ind].type">
                <option>XXXXXX1</option>
                <option>XXXXXX2</option>
                <option>XXXXXX3</option>
              </select>
            </div>
            <div class="col-lg-4">
              <input class="form-control" type="number" min="0" name="qteCommande" [(ngModel)]="lines[ind].qteComm">
            </div>
            <div class="col-lg-4">
              <input class="form-control" type="number" min="0" name="qteRejet" [(ngModel)]="lines[ind].qteRejet">
            </div>
          </div>
        </div>

When I add all the lines at once, the form works perfectly. Now when I try to fill a line then add another line, for some reason, the form resets the lines previously entered.

But when I check my array, it still has the entered values

Can someone explain what is going on here / what I am doing wrong ? Any help would be greatly appreciated.

EDIT : I tried, as suggested by @Ploppy to use trackBy and added an id to my lines. I also added this line to the form :

<p>{{line.id}} | {{line.type}} | {{line.qteComm}} | {{line.qteRejet}}</p>

And this is what's happening :

The form resets but the values are correctly binded.

解决方案

So I finally figured out the problem in my code. My inputs were inside a form, and adding a new line added an input with the same name(Which is not allowed in Agular 2). Replacing my name attributes by name=attribute-{{id}}solved the problem.

<div class="form-group">
      <div class="row" *ngFor="let line of lines; let ind=index;">
        <div class="col-lg-1">
          <i class="fa fa-2x fa-plus-square add-btn" (click)="addLine()" *ngIf="lines[lines.length-1] === line"></i>
        </div>
        <div class="col-lg-3">
          <select class="form-control" name="type-{{ind}}" [(ngModel)]="lines[ind].type">
            <option>XXXXXX1</option>
            <option>XXXXXX2</option>
            <option>XXXXXX3</option>
          </select>
        </div>
        <div class="col-lg-4">
          <input class="form-control" type="number" min="0" name="qteCommande-{{ind}}" [(ngModel)]="lines[ind].qteComm">
        </div>
        <div class="col-lg-4">
          <input class="form-control" type="number" min="0" name="qteRejet-{{ind}}" [(ngModel)]="lines[ind].qteRejet">
        </div>
      </div>
    </div>

Here is a Plunker that summaries everything : Plunker

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09-04 20:22
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