AS3 public variable won't store values - actionscript-3

Question

first time poster here.
So I'm building a "multi-RSS feed reader" and I've broken this into 2 classes, a "TechFeed.as" and a "Feed.as"; The tech feed instantiates multiple feeds by passing URL's to a new Feed object.
My issue at the moment is that in the Feed.as I have a couple public variables which are used in TechFeed.as to display basic details about the feed, however, these variables refuse to retain any value I give them within Feed.as's functions, and are turning up "null".
Edit: Also maybe something to note; TechFeed.as is the main AS file the stage uses.
TechFeed.as
package {
import flash.display.MovieClip;
public class TechFeed extends MovieClip {
private var feed_one:Feed = new Feed("http://feeds.feedburner.com/crunchgear");
private var feed_two:Feed = new Feed("http://feeds.mashable.com/Mashable");
private var feed_three:Feed = new Feed("http://www.engadget.com/rss.xml");
public function TechFeed() {
trace(feed_one.feed_title);
//feed_name.text = feed_one.getFeedTitle();
}
}
}
Feed.as
package {
import flash.net.URLLoader;
import flash.events.Event;
import flash.net.URLRequest;
public class Feed {
//Public variables to display feed info
public var feed_title:XMLList;
public var feed_desc:String;
public var feed_link:String;
//Setting up variables which help load the feeds
private var feedXML:XML;
//Create a loader to load an external URL
private var loader:URLLoader = new URLLoader();
public function Feed(inURL:String = "") {
//Load the xml document
loader.load(new URLRequest(inURL));
loader.addEventListener(Event.COMPLETE,onLoaded);
}
//When the loader had loaded the xml document, pass that into a variable for use.
private function onLoaded(e:Event):void {
feedXML = new XML(e.target.data);
// break down the xml document elements into singular XML array lists
//Feed details
this.feed_title = feedXML.channel.title;
this.feed_link = feedXML.channel.link;
this.feed_desc = feedXML.channel.description;
trace(this.feed_title);
}
}
}
Any help will be greatly appreciated :)
Thanks,
Geoff

Answer 1

Your problem is timing you are trying to write the data from the feed before it is returned from the server.
In this example I assign a function to call back on when the data is loaded.
package {
import flash.display.MovieClip;
public class TechFeed extends MovieClip {
private var feed_one:Feed;
private var feed_two:Feed;
private var feed_three:Feed;
public function TechFeed() {
feed_one= new Feed("http://feeds.feedburner.com/crunchgear",assignResults);
feed_two= new Feed("http://feeds.mashable.com/Mashable",assignResults);
feed_three= new Feed("http://www.engadget.com/rss.xml",assignResults);
}
public function assignResults(value:value):void{
feed_name.text = value;
}
}
}
package {
import flash.net.URLLoader;
import flash.events.Event;
import flash.net.URLRequest;
public class Feed {
//Public variables to display feed info
public var feed_title:XMLList;
public var feed_desc:String;
public var feed_link:String;
//Setting up variables which help load the feeds
private var feedXML:XML;
//Create a loader to load an external URL
private var loader:URLLoader = new URLLoader();
private var _callBackFunc:Function;
public function Feed(inURL:String = "", callBackFunc:Function) {
this._callBackFunc = callBackFunc;
//Load the xml document
loader.load(new URLRequest(inURL));
loader.addEventListener(Event.COMPLETE,onLoaded);
}
//When the loader had loaded the xml document, pass that into a variable for use.
private function onLoaded(e:Event):void {
feedXML = new XML(e.target.data);
// break down the xml document elements into singular XML array lists
//Feed details
this.feed_title = feedXML.channel.title;
this.feed_link = feedXML.channel.link;
this.feed_desc = feedXML.channel.description;
this._callBackFunc(this.feed_title);
}
}
}

Answer 2

If the problem is that feed_one.feed_title is coming up null in the TechFeed() ctor, that is because you are not waiting for the feed to finish loading.
What you aught to do is dispatch an event from the Feed when it is done loading and processing the data, catch it in TechFeed and then use the public variables as you please (this also means that your Feed class will have to subclass EventDispatcher):
In Feed class:
private function onLoaded(e:Event):void {
feedXML = new XML(e.target.data);
// break down the xml document elements into singular XML array lists
//Feed details
this.feed_title = feedXML.channel.title;
this.feed_link = feedXML.channel.link;
this.feed_desc = feedXML.channel.description;
trace(this.feed_title);
dispatchEvent(new Event(Event.COMPLETE));////Dispatch Event
}
In TechFeed class:
public function TechFeed() {
trace(feed_one.feed_title);//This will trace "null"
feed_one.addEventListener(Event.COMPLETE, dataLoaded);//add event listener
}
private function dataLoaded(e:Event):void{
var feed = Feed(e.currentTarget);
feed.removeEventListener(Event.COMPLETE, dataLoaded);//remove event listener to prevent memory leaks
trace(feed.feed_title);// This will trace the correct title
}