[Catalyst] Dispatch matching more than the path?

Garrett Goebel ggoebel at goebel.ws
Mon Aug 21 22:09:38 CEST 2006

I've been looking at Audrey Tang's Jifty::Plugin::Dispatcher::REST  
(http://pugs.blogs.com/pugs/2006/07/rhox_slides_las.html) and DHH's  
"Discovering a world of Resources on Rails" (http:// 
www.loudthinking.com/lt-files/worldofresources.pdf) presentation from  
the 2006 RoR conference. I'm trying to work up something similar for  

My understanding from reading Catalyst's source, is that its  
dispatcher exclusively matches on path. I'm finding that I often want  
to collectively match the path, request method and uri path  
parameters (i.e., what follows the ';' in the path segments of the  
path components of the uri).

I hacked something into the Path and Regex dispatchers to get  
collective matching on method and path working in the prototype. But  
working with path segment params is getting messy. Allowing POST to  
masquerade as a PUT and DELETE method request in order to allow HTML  
forms to submit using these methods means my match rules occassional  
encompass more than I want to match. Which makes me wish an action  
could decline to process a request which was dispatched to it,  
letting the next matching action process it.

Has anyone else approached these problems? Are there any plugin's or  
base classes which already address this need? If not, I'm thinking  
I'll to hack up something that works enough that I could post it to  
the list for dissection.

I've prototyped something similar to Jifty for catalyst. Jifty has a  
nice REST plugin which provides a click-through introspective  
interface to explore the model and perform RESTful operations. It  
uses extensions to specify input and output formats. The examples  
listed below are working in my catalyst prototype. The input/output  
extension examples apply to all the operations not just the one's  
listed in the examples:

#lists models w/ DBIC result sources
GET http://foo.com/=/model       # default response format as html
GET http://foo.com/=/model.js    # response formatted as javascript
GET http://foo.com/=/model.json  # response formatted as json
GET http://foo.com/=/model.yaml  # response formatted as haml
GET http://foo.com/=/model.perl  # response formatted as perl

#list of columns, keys, and relations for "Person" model
GET http://foo.com/=/model/Person

#list all distinct values for comma delimited columns
GET http://foo.com/=/model/Person/id
GET http://foo.com/=/model/Person/given_name,surname

#list all Person records limited by values supplied for columns
GET http://foo.com/=/model/Person/id/32
GET http://foo.com/=/model/Person/given_name,surname/fu,bar

#list all specified fields for all Person records limited by values  
supplied for columns
GET http://foo.com/=/model/Person/id/32/given_name,surname
GET http://foo.com/=/model/Person/given_name,surname/id

#delete all Person records where column(s) = value(s)
DELETE http://foo.com/=/model/Person/id/32
DELETE http://foo.com/=/model/Person/gender/male

#create new person record with columns/values supplied in the body
POST http://foo.com/=/model/Person      #standard body params
POST http://foo.com/=/model/Person.js   #reformat from javascript
POST http://foo.com/=/model/Person.json #reformat from json
POST http://foo.com/=/model/Person.yaml #reformat from yaml

#update new person record with columns/values supplied as body  
PUT http://foo.com/=/model/Person/id/32

In order to allow HTML forms to submit using the PUT or DELETE  
method, I use the same approach as RoR and .NET... i.e., you submit  
via POST using a hidden field to specify the PUT or DELETE method.

I'm now trying to merge this with DHH's RoR push to crudify everything:

   index (GET)  list
     new (GET)   add
    show (GET)  view
    edit (GET)  edit

  create (POST)
    read (GET)
  update (PUT)
destroy (DELETE)

Damn. I have to head out. I'll try to finish up a description of what  
I'm doing to incorporate DHH's ideas. The short version is that he  
uses path segment parameters to control the aspect of how an action  
is handled. For example




P.S. I didn't have a chance to review my post to make sure it follows  
an orderly thread of logic. My apologies. I'll try to clear up an  
questions later this evening.

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