Variable substitution in external XML

Question

I'm loading an external xml file using the Loader class, and
then assigning the loaded content to a variable when the loading is
complete, like this:
function x_loaded(e:Event) {
var rotation_value:String = "-180";
mc_xml = XML(x_loader.data);
If I include in my xml file a value to be substituted, for
example <image rotation={rotation_value}/>, the parsing of
the xml fails when assigning to the mc_xml value.
Is it possible to substitute values in externally loaded xml?
alternatively, is there a way to simply SET the values,
something like image.attribute("rotation")="180";
thanks in advance

Answer 1

Thanks, k
I think all the code that's germane is in my first post, but
here's a bit more detail. It turns out I was using URLLoader, sorry
to confuse the issue. Your help is appreciated. The failure occurs
on the line that reads "mc_xml = XML(x_loader.data);" and the error
message is: "TypeError: Error #1090: XML parser failure: element is
malformed."
my code:
var mc_xml:XML;
var x_loader:URLLoader = new URLLoader();
var x_url:String = "motion.xml";
var x_req:URLRequest = new URLRequest(x_url);
x_loader.addEventListener(Event.COMPLETE,x_loaded);
x_loader.load(x_req);
function x_loaded(e:Event) {
var rotation_value:String = "-180";
mc_xml = XML(x_loader.data);
Here's the (simplified) external xml file. It's generated by
a "Copy motion as ActionScript 3.0" and everything works fine
before I try to substitute some variables in the xml. You can see
the substitution in the penultimate line.
<Motion duration="20" xmlns="fl.motion.*"
xmlns:geom="flash.geom.*" xmlns:filters="flash.filters.*">
<source>
<Source frameRate="25" x="784.3" y="78.1" scaleX="1"
scaleY="1" rotation="180" elementType="movie clip"
instanceName="mc" symbolName="Symbol 2">
<dimensions>
<geom:Rectangle left="0" top="0" width="288"
height="209"/>
</dimensions>
<transformationPoint>
<geom:Point x="0.2586805555555556"
y="0.3923444976076555"/>
</transformationPoint>
</Source>
</source>
<Keyframe index="0">
<tweens>
<SimpleEase ease="0"/>
</tweens>
</Keyframe>
<Keyframe index="19" x="-709.8" y="3.9000000000000057"
rotation={rotation_value} />
</Motion>
Thanks in advance for any insight you can provide