The paperCrane’s view from the reverseFold

I finally got fed up with recompiling our Flex application for the different servers I had to deploy to and decided to have it automatically figure out where it is and configure itself. This should have been relatively simple as the swf’s URL is known by the Flash player and was always available in Flash as _root._url (or _root[”_url”]). I knew that Flex had to have this information available so I looked it up.

Sure enough, there is a place in the DisplayObject where you can get this info. DisplayObject.loaderInfo.url. Further looking showed that the Application object should have the loaderInfo. I added some code to test this in a function which was run on the “creationComplete” event and….the loaderInfo object is null.

I then looked further to see if there was another object that maybe had the loaderInfo I needed. The root proprty is supposed to give you the root object of the SWF and this should have the right loaderInfo, right? Nope, still null on “creationComplete”.

I now got suspicious and added some code to look at the URL on the click of a button. Sure enough this code was able to access the loaderInfo and hence get the URL.

So why is the loaderInfo not loaded when the application is created? If I can’t get the URL I can’t do my configuration as there is no other event I know of which I can listen for to set the configuration.

I now dove into the Application code in the Flex framework. I soon found the _url property which is declared as mx_internal. I remembered reading Daniel R’s blog post about mx_internal and quickly set up my code to use mx_internal::_url. Success, this is set on creationComplete.

Now to ask Adobe why we don’t have access to loaderInfo until after the creationComplete event….

UPDATE: After more searching I found the FlexEvent.APPLICATION_COMPLETE event. If you try to access Application.loaderInfo.url when this event is called it is set.