[Catalyst] XPath, DOM problem

[Tomas Doran]

On 8 Jul 2008, at 09:00, Herr Verdieck Götz wrote:

> Hi,
>
> I try to generate a site content menu from a xml file.
>
> In my TT file I have the following syntax:
> [%
>  # USE prod_tree = XML.Simple('config/xml/hele_de_tree.xml'); # OK  
> this works
>
>
>  USE xpath = XML.XPath('config/xml/hele_de_tree.xml');  # ERROR
>  #USE dom = XML.DOM;
>  #prod_tree = dom.parse('config/xml/sitemap.xml'); # ERROR
>
> -%]
>
> The XML.Simple version is ok, but
> when I try to use XPath - or DOM-  I get the message:
> Errot message:
> Couldn't render template "plugin error - Cannot open file 'config/ 
> xml/hele_de_tree.xml' at /Library/Perl/5.8.8/XML/XPath.pm line 53.
>
> I use Catalyst 5.7014 and Template-Toolkit-2.19.
>
>
> I also tested XPath with a small script without problems. So the  
> combination with TT or Catalyst causes the error.

I'd guess it's not finding the correct path..

You probably want to say something like:

USE xpath = XML.XPath(c.path_to('config', 'xml', 'hele_de_tree.xml'));

so that you are not relying on the PWD being what you expect.

However, there is a good argument that you shouldn't be doing this in  
a template - this is data/domain logic, and therefore separation of  
concerns says that this should be in the Model.

I'd create a model which creates the appropriate data structures for  
you, and a controller which defines the file path, feeds it to the  
model, and then pushes the returned data structure/objects into the  
stash, allowing the templates to them simply iterate over them.

This buys you a lot of future proofing, as if you start wanting to  
pre-process your XML in some way before passing it to the template,  
you can trivially do so, without having to change any of the code in  
your templates.

Cheers
Tom