Angular2-单击按钮更新模型

Question

When using the angular2 ngModel for two-way data binding:

<input [(ngModel)]="heroName">

Is there a way to only update the model once a button is clicked? Or be able to cancel the changes that the user made to the input control? I am aware of the other approach where we can split the [(ngModel)] in its [] and () and only update the input on blur or when the Enter key is pressed etc - but this is not what I want.

I need this behavious because, the user must be able to cancel the changes. Thanks

Answer 1

You can do following for that,

DEMO : http://plnkr.co/edit/OW61kGGcxV5MuRlY8VO4?p=preview

{{heroName}}<br>
<input [ngModel]="heroName" #change> <br>
<br>
<button (click)="update(change.value)">Update Model</button>

---

export class App {
  heroName="Angular2";
  update(value){
    console.log('value before button click' + this.heroName);
    this.heroName=value;
    console.log('value after button click' + this.heroName);
  }
}

Answer 2

You can create a new property for the form binded property.

Would look like this

<input [(ngModel)]="formHeroName" #change> <br>
{{selectedHeroName}}
<br>

Update Model Cancel

export class App implements OnInit {
selectedHeroName="Angular2";
formHeroName = "";

ngOnInit() {
  this.formHeroName = this.selectedHeroName;
}

update(){
  this.selectedHeroName= this.formHeroName;
}

cancel() {
  this.formHeroName = this.selectedHeroName;
}
}

See plunker for example - http://plnkr.co/edit/0QEubJDzlgs0CdnKrS8h?p=preview

Answer 3

You can separate your "live" data from your "valid" data.

Try something like this:

<input [(ngModel)]="live.heroName">
<button (click)="save()">Save</button>
<button (click)="reset()">Reset</button>

And the controller:

live = { heroName: '', heroPower: '' };
valid = { heroName: '', heroPower: '' };

save() {
    this.valid = Object.assign({}, this.live);
}

reset() {
    this.live = Object.assign({}, this.valid);
}