带有JSON对象的ngFor-Angular 2 ngmodel透视图

Question

I have been trying to do a simple task of taking an input in textbox and listing the same. The sample code is below: Example.html:

<label>Name:</label>
<input type="text" [(ngModel)]="user.name" placeholder="Enter a name here">

<!-- conditionally display `yourName` -->
<button (click)="getData(user)">Add</button>
<hr>
<ul>
    <li *ngFor="let rec of record">{{rec.name}}</li>
</ul>

And code in example.ts is below:

 record:any[]=[];
  user={"name":""};
  getData(username:any){
    this.record.push(username);
    console.log(JSON.stringify(this.record));
  }

Th problem i face is, when i insert the second input , even the first input changes as second as both refer to the same ngModel.For instance, if i add "GG" as input, first record will be GG . When i enter "HH" then, first record GG changes to HH and result will be HH and HH. Please help me understand where i went incorrect and help solve this.

Answer 1

Since your object has same key name every time while pushing the object will get updated with new value so how have do like this

 this.record.push(Object.assign({}, username));

Read about Object.assign() from here https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

Answer 2

You have understood correctly that the problem is caused by the objects having same reference. As you are trying to store user details in a simple object you can easily clone the object by changing

this.record.push(username);

TO

this.record.push(_.clone(username));

The _.clone is a lodash function which will pass a new object instead of a reference.

You can also try a quick fix ( highly discouraged due to performance reasons );

this.record.push(JSON.parse(JSON.stringify(username)));