[Catalyst] Input filtering -- XMLRPC dispatch type

[Bill Moseley]

I'm looking for some design advice:

I'm exposing many controllers to XMLRPC requests.  I have an XMLRPC
dispatch type so for many of the controllers it's just a matter of
adding an XMLRPC( 'some.api.method' ) sub attribute to existing actions.

In many cases the arguments passed in the XMLRPC need to be mapped to
the parameters that the controller needs.  Therefore, I need to call
some code before the action is run to do this mapping.

This is basically action-specific input filtering.

My question is this:

    Where do these action and XMLRPC specific methods go?


One option would be in the controller itself.

    package MyApp::User;
    use base 'Catalyst::Controller';

    # List all users
    sub list_all : Local : XMLRPC( 'user.list_all' ) {}


    # Method that is called to map parameters
    # before list_all() is called.
    sub xmlrpc_begin_list_all {}

But, then I'm cluttering up the controllers.  Plus, there may be more
than just XMLRPC so I don't want to have <api_type>_begin_<action>
methods for each type.  Gets messy.


Another approach would be a separate namespace for the mapping
methods:

    package MyApp::Filter::XMLRPC::User;

    # map parameters for the MyApp::User::list_all action
    sub list_all {}


How would you do this?


-- 
Bill Moseley
moseley at hank.org