Book Image

Angular Services

Book Image

Angular Services

Overview of this book

A primary concern with modern day applications is that they need to be dynamic, and for that, data access from the server side, data authentication, and security are very important. Angular leverages its services to create such state-of-the-art dynamic applications. This book will help you create and design customized services, integrate them into your applications, import third-party plugins, and make your apps perform better and faster. This book starts with a basic rundown on how you can create your own Angular development environment compatible with v2 and v4. You will then use Bootstrap and Angular UI components to create pages. You will also understand how to use controllers to collect data and populate them into NG UIs. Later, you will then create a rating service to evaluate entries and assign a score to them. Next, you will create "cron jobs" in NG. We will then create a crawler service to find all relevant resources regarding a selected headline and generate reports on it. Finally, you will create a service to manage accuracy and provide feedback about troubled areas in the app created. This book is up to date for the 2.4 release and is compatible with the 4.0 release as well, and it does not have any code based on the beta or release candidates.
Table of Contents (15 chapters)
Angular Services
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Working with data via lists


You might think, we can re-factor the onChange() method, so it can differentiate between checked and un-checked items and save only selected news. That might solve a part of the issue, but the main problem (objects being overwritten) still exists.

The solution relies on another AngularFire object called FirebaseListObservable. With the list objects we can push entries without losing the previous objects. In our previous example, we updated the code and replaced the object.set() method with the list.push() method as follows:

// src/app/collector/collector.component.ts 
//... 
import {AngularFire, FirebaseListObservable} from "angularfire2/angularfire2"; 
//... 
export class CollectorComponent { 
  //... 
  constructor (collectorService: CollectorService, af: AngularFire) { 
    //... 
    this.items = af.database.list('/Collector'); 
  } 
 
  onChange(item){ 
    this.items.push(item); 
  } 
} 

Now inside the collector page, select a few news entries from the collected...