Route and View Examples

Here are the most common kinds of routes and views.

1. Fixed controller and action.

   # Pylons
   map.connect("faq", "/help/faq", controller="help", action="faq")
   class HelpController(Base):
       def faq(self):
           ...
   

   # Pyramid
   config.add_route("faq", "/help/faq")
   @view_config(route_name="faq", renderer="...")
   def faq(self):   # In some arbitrary class.
       ...
   

   .

2. Fixed controller and action, plus other routing variables.

   # Pylons
   map.connect("article", "/article/{id}", controller="foo",
       action="article")
   class FooController(Base):
       def article(self, id):
           ...
   

   # Pyramid
   config.add_route("article", "/article/{id}")
   @view_config(route_name="article")
   def article(self):   # In some arbitrary class.
       id = self.request.matchdict["id"]
   

   .

3. Variable controller and action.

   # Pylons
   map.connect("/{controller}/{action}")
   map.connect("/{controller/{action}/{id}")
   

   # Pyramid
   # Not possible.
   

   You can’t choose a view class via a routing variable in Pyramid.

4. Fixed controller, variable action.

   # Pylons
   map.connect("help", "/help/{action}", controller="help")
   

   # Pyramid
   config.add_route("help", "/help/{action}")
   
   @view_config(route_name="help", match_param="action=help", ...)
   def help(self):   # In some arbitrary class.
       ...
   

   The ‘pyramid_handlers’ package provides an alternative for this.

Other Pyramid examples:

# Home route.
config.add_route("home", "/")

# Multi-action route, excluding certain static URLs.
config.add_route("main", "/{action}",
    path_info=r"/(?!favicon\.ico|robots\.txt|w3c)")

pyramid_handlers

“pyramid_handlers” is an add-on package that provides a possibly more convenient way to handle case #4 above, a route with an ‘action’ variable naming a view. It works like this:

    # In the top-level __init__.py
    from .handlers import Hello
    def main(global_config, **settings):
        ...
        config.include("pyramid_handlers")
        config.add_handler("hello", "/hello/{action}", handler=Hello) 

    # In zzz/handlers.py
    from pyramid_handlers import action
    class Hello(object):
        __autoexpose__ = None

        def __init__(self, request):
            self.request = request

        @action
        def index(self):
            return Response('Hello world!')

        @action(renderer="mytemplate.mak")
        def bye(self):
            return {}

The add_handler method (line 6) registers the route and then scans the Hello class. It registers as views all methods that have an @action decorator, using the method name as a view predicate, so that when that method name appears in the ‘action’ part of the URL, Pyramid calls this view.

The __autoexpose__ class attribute (line 11) can be a regex. If any method name matches it, it will be registered as a view even if it doesn’t have an @action decorator. The default autoexpose regex matches all methods that begin with a letter, so you’ll have to set it to None to prevent methods from being automatically exposed. You can do this in a base class if you wish.

Note that @action decorators are not recognized by config.scan(). They work only with config.add_hander.

User reaction to “pyramid_handlers” has been mixed. A few people are using it, but most people use @view_config because it’s “standard Pyramid”.

Resouce routes

“pyramid_routehelper” provides a config.add_resource method that behaves like Pylons’ map.resource. It adds a suite of routes to list/view/add/modify/delete a resource in a RESTful manner (following the Atom publishing protocol). See the source docstrings in the link for details.

Note: the word “resource” here is not related to traversal resources.