Trivial traversal-in-views example; hopefully this adds an easy way t…

…o quickly 'get' traversal

CONTRIBUTORS.txt

@@ -105,4 +105,5 @@ Blaise Laflamme, 12/27/2010
 Casey Duncan, 12/27/2010
 Michael Merickel, 3/30/2011
 Charlie Choiniere, 4/23/2011
-Steve Piercy, 5/10/2011
+Steve Piercy, 5/10/2011
+Paul Winkler, 1/30/2012

index.rst

@@ -27,6 +27,7 @@ The Pyramid Cookbook presents topical, practical usages of :mod:`Pyramid`.
    deployment/index.rst
    porting
    testing
+   traversal_in_views
    traversal
    cmf/index.rst
    mac_install

traversal.rst

@@ -152,3 +152,7 @@ This is simpler and more readable because we are using URL dispatch to take
 care of the hardcoded URLs at the top of the tree, and we are using traversal
 only for the arbitrarily nested subdirectories.
 
+See Also
+~~~~~~~~
+
+- :doc:`traversal_in_views`

traversal_in_views.rst

@@ -0,0 +1,78 @@
+Using Traversal in Pyramid Views
+=================================
+
+A trivial example of how to use :term:`traversal` in your view code.
+
+You may remember that a Pyramid :term:`view` is called with a
+:term:`context` argument:
+
+.. code-block:: python
+
+    def my_view(context, request):
+        return render_view_to_response(context, request)
+
+
+When using traversal, ``context`` will be the :term:`resource` object
+that was found by traversal.  Configuring which resources a view
+responds to can be done easily via either the ``@view.config``
+decorator...
+
+.. code-block:: python
+
+
+    from models import MyResource
+
+    @view_config(context=MyResource)
+    def my_view(context, request):
+        return render_view_to_response(context, request)
+
+or via ``config.add_view``:
+
+.. code-block:: python
+
+    from models import MyResource
+    config = Configurator()
+    config.add_view('myapp.views.my_view', context=MyResource)
+
+Either way, any request that triggers traversal and traverses to a
+``MyResource`` instance will result in calling this view with that
+instance as the ``context`` argument.
+
+Optional: Using Interfaces
+--------------------------
+
+If your resource classes implement :term:`interfaces <interface>`,
+you can configure your views by interface. This is one way to decouple
+view code from a specific resource implementation::
+
+
+    # models.py
+    from zope.interface import implements
+    from zope.interface import Interface
+    
+    class IMyResource(Interface):
+        pass
+    
+    class MyResource(object):
+        implements(IMyResource)
+    
+    # views.py
+    from models import IMyResource
+    
+    @view_config(context=IMyResource)
+    def my_view(context, request):
+        return render_view_to_response(context, request)
+
+
+See Also
+--------
+
+- :doc:`traversal`
+
+- The "Virginia" sample application: https://github.com/Pylons/virginia/blob/master/virginia/views.py
+
+- ZODB and Traversal in Pyramid tutorial: http://docs.pylonsproject.org/projects/pyramid/en/latest/tutorials/wiki/index.html#bfg-wiki-tutorial
+
+- "Pyramid Traversal and Mongodb": http://kusut.web.id/2011/03/27/pyramid-traversal-and-mongodb/
+
+- Resources which implement interfaces: http://readthedocs.org/docs/pyramid/en/latest/narr/resources.html#resources-which-implement-interfaces