Angular2: Two-way data binding on component dynamically inserted using DynamicComponentLoader

Question

I am developing an Angular2 app, and I faced a problem:

I have a set of different objects that can be selected using UI. Each of this objects has a set of options (different for different objects) that could be edited using UI. Now, I am using DynamicComponentLoader to insert a specific component for currently selected object, so it can handle its options correctly. The problem is that I don't know how to bind data of currently selected object to a dynamically inserted options component.

@Component({
  selector: 'dynamic',
  template: `<div>Options:</div>
             <div>Property1: <input type="number" /></div>
             <div>Property2: <input type="text" /></div>`
  // template: `<div>Options:</div>
  //           <div>Property1: <input type="number" [(ng-model)]="currentSelection.property1" /></div>
  //           <div>Property2: <input type="text" [(ng-model)]="currentSelection.property1" /></div>`
})
class DynamicComponent {

}


@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>Selected: {{currentSelection.name}}!</h2>
      <div  #container></div>
    </div>
  `
})
class App {
  currentSelection = {name: 'Selection1', property1: 10, property2: 'test'};

  constructor(private loader: DynamicComponentLoader, private elementRef: ElementRef) {
    loader.loadIntoLocation(DynamicComponent, elementRef, 'container');
  }
}

Here is a plunker to help you understand my question:

the only example there is around is this github.com/angular/angular/blob/… — Angular University
– Angular University, Commented Nov 4, 2015 at 8:16

Abdulrahman Alsoghayer · Accepted Answer · 2016-02-18 03:25:22Z

With angular2 and Rxjs, "Observables" are almost always the answer.

If i understood your problem correctly, you need to make your DynamicComponent an "Observer" and your container "an Observable or even better a Subject (In case your container needs to subscribe to another observable to receive selections from)". Then, after loading your dynamic component, subscribe it to your container.

Whenever the selection changes on your container, you push the new selection to your subscribers. This way, you can load multiple dynamic components and all will receive your pushes.

The Container:

class App {
  currentSelection = {};
  selections = [
    {name: 'Selection1', property1: 10, property2: 'test'},
    {name: 'Selection2', property1: 20, property2: 'test2'}
  ];
  subject:Subject<any> = new Subject();

  constructor(private loader: DynamicComponentLoader, private elementRef: ElementRef) {
  }

  ngOnInit(){
    this.loader.loadIntoLocation(DynamicComponent, this.elementRef, 'container', this.injector)
    .then(compRef =>this.subject.subscribe(compRef.instance));
    // subscribe after loading the dynamicComponent
  }

  // set the new selection and push it to subscribers
  changeSelection(newSelection){
    this.currentSelection = newSelection;
    this.subject.next(this.currentSelection);
  }
}

The Observer:

class DynamicComponent implements Observer{
  public currentSelection = {};

  next(newSelection){
    this.currentSelection = newSelection;
  }
}

Here is your plunker working after my edits, "provided I changed the imports to the newest angular beta.6"

I know this is a quite old question. But hopefully someone will benefit from this answer.

Anshul · Accepted Answer · 2016-03-26 19:42:31Z

2

Here is what you can do, move your code from constructor to ngOnInit and use promises for assigning dynamic value.

ngOnInit(){
    this.dynamicComponentLoader.loadIntoLocation(DynamicComponent, this.elementRef,'container').then((component)=>{
        component.instance.currentSelection = currentSelection;
    });
}

answered Mar 26, 2016 at 19:42

Anshul

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