Question

I need to bind a property to an edit control and have the control write its value back to the same property. The problem is, I’m setting the source value before the control is created:

<mx:Panel>
    <mx:Script>
        <![CDATA[
            [Bindable] public var editedDocument: XML;
        ]]>
    </mx:Script>
    <mx:TextInput id="docLabel" text="{editedDocument.@label}"/>
    <mx:Binding source="docLabel.text" destination="editedDocument.@label"/>
</mx:Panel>

I call this like so:

var xmlDoc: XML = <document label="some label" />;
var myPanel: MyPanel = new MyPanel();
myPanel.editedDocument = xmlDoc;
parent.addChild(myPanel);

What happens is this:

• the docLabel text field ends up blank (equal to “”)
• the xmlDoc’s @label attribute is set to “”

What I want is this:

• the docLabel text field should contain “some label”
• the xmlDoc’s @label attribute should change only when the docLabel’s text property changes.

How do I accomplish this, using Flex 3?

Edit

I have also tried this:

<mx:Panel>
    <mx:Script>
        <![CDATA[
            [Bindable] public var editedDocument: XML;
        ]]>
    </mx:Script>
    <mx:TextInput id="docLabel"/>
    <mx:Binding source="editedDocument.@label" destination="docLabel.text"/>
    <mx:Binding source="docLabel.text" destination="editedDocument.@label"/>
</mx:Panel>

The result is the same.

Answer 1

You can try using BindingUtils to programmatically create the binding after the class has been created:
http://life.neophi.com/danielr/2007/03/programmatic_bindings.html

There are many variations of this that I’ve used to tackle similar problems. If you can’t figure it out from the link post a comment and I’ll dig through my source code and see what I can find.

private function init():void 
{
  var xmlDoc: XML = <document label="some label" />;
  var myPanel: MyPanel = new MyPanel();
  myPanel.editedDocument = xmlDoc;
  parent.addChild(myPanel);
  BindingUtils.bindProperty(docLabel, "text", editedDocument, "label");

  //or maybe it should be one of these, I have not done binding to an XML attribute before
  BindingUtils.bindProperty(docLabel, "text", editedDocument, "@label");
  BindingUtils.bindProperty(docLabel, "text", editedDocument, "{@label}");
}