Bind to object property - apache-flex

Question

AS
[Bindable]
var object:Object = {
property: "Property"
};
MXML
<s:Label text="{object.property}"/>
The labels text will be "Property", but if object.property is changed, the label isn't updated. Is there any way around this?

Answer 1

Properties of an object or collection will not dispatch a property change event unless implemented.
Likewise to your example, a change to an Array element will not be bound.
Collections such as ArrayCollection wrap objects within a proxy to dispatch events for binding.
Use an ObjectProxy to dispatch changes to your object.
Instantiate an ObjectProxy and listen for PropertyChangeEvent:
objectProxy = new ObjectProxy(object);
objectProxy.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, propertyChangeHandler);
Access your object via the proxy, such as setting a property named 'property':
objectProxy.property = "Hello, world";
This example creates an ObjectProxy with a timer to change the 'property' member every second:
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
minWidth="955"
minHeight="600"
creationComplete="creationCompleteHandler(event)">
<fx:Script>
<![CDATA[
import mx.events.FlexEvent;
import mx.events.PropertyChangeEvent;
import mx.utils.ObjectProxy;
private var object:Object = {};
private var objectProxy:ObjectProxy;
private var timer:Timer;
protected function creationCompleteHandler(event:FlexEvent):void
{
objectProxy = new ObjectProxy(object);
objectProxy.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, propertyChangeHandler);
timer = new Timer(1000);
timer.addEventListener(TimerEvent.TIMER, timerHandler);
timer.start();
}
protected function propertyChangeHandler(event:PropertyChangeEvent):void
{
label.text = (event.source).property;
}
protected function timerHandler(event:TimerEvent):void
{
objectProxy.property = Math.random() * 1000;
}
]]>
</fx:Script>
<s:Label id="label" />
</s:Application>

Answer 2

You're binding to object itself. That means, that the text of the label would change only if reference to object will be changed.
object={property:"Hello World"}
In this case the binding will do the job.
If you want the text to update after some property change, you should make this property Bindable.
public class MyObject {
[Bindable]
public var property:String;
}
Then declare the variable of class MyObject and bind to its property.