DataBinding a Proxy to a Mediator

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This has been a topic I have wanted to mention for a while now, actually since my Combining the PureMVC StateMachine Utility with Slacker post as I use this particular logic in there. When I first used a MVC framework primarily PureMVC one of the concepts I toyed around with was different approaches for getting data from the Proxy to the Mediator. This decision is situation dependent so a simple one shoe fits all doesn’t apply here, but for the purposes of data getting updated in a proxy and the necessary requirement to ensure a Mediator gets informed of this change to the data you could:

  • Adhering to the PureMVC logic you could fire off a notification from your Proxy and register an interest in your Mediator passing the data as the notification body.
  • You could do the above but create an instance of your Proxy in the Mediator and directly access the data within a method triggered by an Event for example.

Here’s another suggested approach.

I have mentioned that I personally don’t see a major problem with a simple reference to the Proxy in the Mediator for the simple fact your just reaching in and grabbing data, no biggie but I understand that some have concerns with this approach. However I don’t have a major problem with getting the instance of a Proxy from the facade and having this reference in my Mediator. With this I can then have a much better handling for keeping data in a View updated using BindingUtils. Using my previous blog post as an example I would define a getter and setting in the Proxy as below:

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[Bindable(event="usernameChanged")]
public function get username():String
{
    return __username;
}
        
public function set username( val:String ):void
{
     if ( __username != val ) 
     { 
         __username = val; 
                
         eventDispatcher.dispatchEvent ( new Event("usernameChanged") ); 
      } 
}

And then in the Mediator:

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protected function get app():index
{
    return viewComponent as index;
}

// Bind data from the HandleLoginProxy to variable/component in view
BindingUtils.bindProperty( app.log_txt, 'text', lgnPrx, ["username"]);

And that’s it! Now when ever the data in my Proxy is updated I know through DataBinding that the View will be updated with the latest data value.

If you would like a simple introduction into PureMVC then be sure to read my post showing a super simple example http://www.newtriks.com/?p=352. Also look at a real world example I build using the above logic and States http://www.newtriks.com/?p=363.

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