Newbie: binding actionscript var to textinput

Question

Hi,
I'm just starting with flex, and have a simple question on
bindings. I've created the following application (using flex3 beta
3, and flexbuilder):
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="absolute">
<mx:Script>
<![CDATA[
[Bindable]
public var customerName:String = "customerName";
]]>
</mx:Script>
<mx:TextInput text="{customerName}" x="187" y="92"/>
<mx:Text text="{customerName}" x="368" y="94"/>
<mx:Button click="customerName += 'z'" x="473" y="92"
label="add z"/>
</mx:Application>
The problem: the variable customerName isn't changed when i
enter some text in the textinput. Pressing the button does the
expected thing: changes the variable, which is displayed correctly
by the textinput and text components.
My goal is to create a datamodel using an actionscript
object. I've seen some examples where the datamodel is bound to the
textinput (the other way around), but it seems to me that it would
be better not to tie a datamodel to one single input component. I
may want to modify the data using multiple components.
Thanks,
Andrej

Answer 1

My 2 cents: There is often a misconception that when making a
variable bindable, it is a two-way binding, in other words, the
entity that is bound to the variable will be updated automatically
AND the variable will be updated if the entity's value changes (a
circular binding).
Making your variable [Bindable] means that there is a single
observer, like your TextInput, of a variable, like customerName. If
the customerName variable changes, then the TI will change, not the
other way around.
Your approach of using the Binding tag with a reciprocal
source and destination should be fine.
My approach usually is to set the initial value I want
displayed in the TI from elsewhere. Then the TI is strictly used as
the control to input data in order to update a variable on the
'change' event. I often bind to a function that'll automatically
perform XYZ for me on a specific event.
TS