Recently I have been lucky enough to be working on a project that uses LCDS so I don’t have to write XML translators – all the objects arrive from server ready typed – it is soooo much easier and saves an awful lot of time.
At home though I have started working with the Picasa data API which means I am back to writing translators.
This is a job I really don’t like – it never works the first time and takes a lot of trial and error to get it write. I am actually going to write a base translator class to make it a bit easier the next time I have to do it.
Getting to grips with xml can be tricky but when namespaces are involved it gets exponentially more difficult and annoying!
I’ll make a note of the syntax of how to deal with namespaces here so that next time I’ve forgotten how to do it I can look it up.
I am trying to retrieve the href of the link node below with the relevance of self:
<feed
xmlns='http://www.w3.org/2005/Atom'
xmlns:gphoto='http://schemas.google.com/photos/2007'
>
<link
rel='alternate'
type='text/html'
href='http://picasaweb.google.com/Giles.Roadnight'
/>
<link
rel='self'
type='application/atom+xml'
href='http://picasaweb.google.com/data/feed/api/user/Giles.Roadnight'
/>
</feed>
My first attempt was as follows:
var href : String = xml.link(@rel=’self’)[ 0 ]@href;
but that didn’t work. The give away is this line:
xmlns='http://www.w3.org/2005/Atom'
declaring the default namespace for the xml. What worked in the end was this:
var atom : Namespace = new Namespace( "http://www.w3.org/2005/Atom" );
var href : String = xml.atom::link.( @rel == 'self' )[ 0 ]@href;
Hopefully that’ll save me (and maybe you) a few hours in the future.
