websocket - Angular2 View Not Changing After Data Is Updated

Question

I am trying to update my view after a websocket event returns updated data.

I injected a service into my app and call getData() method on the service. This method emits a socket.io event to my NodeJS server which in turn performs an external api call and parses some data. The NodeJS server then emits a success event with the new data that I listen for in my service. When the success event is returned I then update my property on the service that is referenced in my view.

However no matter what I try I cannot get the data to show once the property is updated.

I have searched for a few days now and all I find are blog posts that say this change should be seamless, or that I need to incorporate zone.js somehow, or to try the same logic using forms (however im trying to do this without user interaction). Nothing seems to work for me and I am getting a bit frustrated.

For example:

Lets say I receive an array of strings that I want to create an unsorted list with.

app.ts

import {Component, View, bootstrap, NgFor} from 'angular2/angular2';
import {MyService} from 'js/services/MyService';

// Annotation section
@Component({
    selector: 'my-app',
    viewInjector: [MyService]
})
@View({
    templateUrl: 'templates/my-app.tpl.html',
    directives: [NgFor]
})

class MyComponent {
    mySvc:MyService;

    constructor(mySvc:MyService) {
        this.mySvc = mySvc;
        this.mySvc.getData();
    }
}   

bootstrap(MyComponent, [MyService]);

MyService.ts

let socket = io();
export class MyService {
    someList:Array<string>;

    constructor() {
        this.initListeners();
    }

    getData() {
        socket.emit('myevent', {value: 'someValue'});
    }

    initListeners() {
        socket.on('success', (data) => {
            self.someList = data;
        });
    }
 }

my-app.tpl.html

<div>
    <h2>My List</h2>
    <ul>
        <li *ng-for="#item of mySvc.myList">Item: {{item}}</li>
    </ul>
</div>

Interesting enough, I have found that If I incorporate a timeout within my component that updates some arbitrary property that I set on the view after the someList property is updated from the success callback then both property values are updated correctly at the same time.

For instance:

new app.ts

    import {Component, View, bootstrap, NgFor} from 'angular2/angular2';
    import {MyService} from 'js/services/MyService';

    // Annotation section
    @Component({
        selector: 'my-app',
        viewInjector: [MyService]
    })
    @View({
        templateUrl: 'templates/my-app.tpl.html',
        directives: [NgFor]
    })

    class MyComponent {
        mySvc:MyService;
        num:Number;

        constructor(mySvc:MyService) {
            this.mySvc = mySvc;
            this.mySvc.getData();
            setTimeout(() => this.updateNum(), 5000);
        }

        updateNum() {
            this.num = 123456;
        }
    }   

    bootstrap(MyComponent, [MyService]);

new my-app.tpl.html

<div>
    <h2>My List {{num}}</h2>
    <ul>
        <li *ng-for="#item of mySvc.myList">Item: {{item}}</li>
    </ul>
</div>

So how should I go about getting angular2 to recognize that the data has changed after the 'success' event without updating some other property?

Is there something I am missing with the use of the NgFor directive?

Answer 1

So I finally found a solution that I like. Following the answer in this post How to update view after change in angular2 after google event listener fired I updated myList within zone.run() and now my data is updated in my view like expected.

MyService.ts

/// <reference path="../../../typings/tsd.d.ts" />

// Import
import {NgZone} from 'angular2/angular2';
import {SocketService} from 'js/services/SocketService';

export class MyService {
    zone:NgZone;
    myList:Array<string> = [];
    socketSvc:SocketService;

    constructor() {
        this.zone = new NgZone({enableLongStackTrace: false});
        this.socketSvc = new SocketService();
        this.initListeners();
    }

    getData() {
        this.socketSvc.emit('event');
    }

    initListeners() {
        this.socketSvc.socket.on('success', (data) => {
            this.zone.run(() => {
                this.myList = data;
                console.log('Updated List: ', this.myList);
            });
        });
    }
 }