merge handlers chapter into views chapter

1 files changed, 252 insertions, 10 deletions

diff --git a/docs/narr/views.rst b/docs/narr/views.rst
index c66da636f..447385458 100644
--- a/docs/narr/views.rst
+++ b/docs/narr/views.rst
@@ -198,6 +198,58 @@ related view callables.
 	No matter which view calling convention is used, the view code always
 	has access to the context via ``request.context``.
 
+Defining a Set of View Callables Using a Handler
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Along with normal view callable functions, instances, and classes,
+:app:`Pyramid` provides the special concept of a :term:`view handler`.  View
+handlers are a convenience for :term:`URL dispatch` users.  The concept of a
+view handler is analogous to a "controller" in Pylons 1.0.  Using a view
+handler instead of a plain function or class :term:`view callable` makes it
+unnecessary to call :meth:`pyramid.config.Configurator.add_route` (and/or
+:meth:`pyramid.config.Configurator.add_view`) "by hand" multiple times,
+making it more pleasant to register a collection of views as a single class
+when using :term:`url dispatch`.  The view handler machinery also introduces
+the concept of an ``action``, which is used as a :term:`view predicate` to
+control which method of the handler is called.
+
+.. note:: 
+
+   View handlers are *not* useful when using :term:`traversal`, only when using
+   :term:`url dispatch`.  
+
+The view handler class is initialized by :app:`Pyramid` in the same manner as
+a view *class*.  Its ``__init__`` is called with a request object (see
+:ref:`class_as_view`) as its argument when a request enters the system which
+corresponds with a view handler registration made during configuration.
+After the view handler class is instantiated, a method on the instance is
+called. Typically, each method of the handler is used as a view callable.
+The methods which are called depends on the view handler's configuration.
+
+Here's an example view handler class:
+
+.. code-block:: python
+    :linenos:
+    
+    from pyramid.response import Response
+   
+    from pyramid.view import action
+   
+    class Hello(object):
+        def __init__(self, request):
+            self.request = request
+       
+        def index(self):
+            return Response('Hello world!')
+
+        @action(renderer="mytemplate.mak")
+        def bye(self):
+            return {}
+
+Handlers are added to application configuration via the
+:meth:`pyramid.config.Configurator.add_handler` API, as described in
+:ref:`using_add_handler`.
+
 .. index::
    single: view response
    single: response
@@ -524,8 +576,8 @@ using your own response object, you will need to ensure you do this yourself.
 
 .. _view_configuration:
 
-View Configuration: Mapping a Resource Type to a View
------------------------------------------------------
+View Configuration: Mapping a Resource or URL Pattern to a View Callable
+------------------------------------------------------------------------
 
 A developer makes a :term:`view callable` available for use within a
 :app:`Pyramid` application via :term:`view configuration`.  A view
@@ -547,16 +599,21 @@ View configuration is performed in one of these ways:
   :meth:`pyramid.config.Configurator.add_view` and
   :ref:`mapping_views_using_imperative_config_section`.
 
-Both of these mechanisms is completely equivalent to the other.
+- By specifying a view within a :term:`route configuration`.  View
+  configuration via a route configuration is performed by using the
+  :meth:`pyramid.config.Configurator.add_route` method, passing a ``view``
+  argument specifying a view callable.
 
-.. note:: You can also add view configuration by adding a ``<view>``
-   declaration to :term:`ZCML` used by your application as per
-   :ref:`mapping_views_using_zcml_section` and :ref:`view_directive`.
+- by using the :meth:`pyramid.config.Configurator.add_handler` against a
+  :term:`view handler` class (useful only for :term:`URL dispatch`
+  applications).
 
-A view configuration might also be performed by virtue of :term:`route
-configuration`.  View configuration via route configuration is performed by
-using the :meth:`pyramid.config.Configurator.add_route` method to create a
-route with a ``view`` argument.
+.. note:: You can also add view configuration by adding a ``<view>`` or
+   ``<handler>`` declaration to :term:`ZCML` used by your application as per
+   :ref:`mapping_views_using_zcml_section`, :ref:`view_directive`, and
+   :ref:`handler_directive`.
+
+A view configuration might also be performed by virtue of 
 
 .. note:: ZCML users can use :ref:`route_directive` to perform the same task.
    See also :ref:`zcml_route_configuration`.
@@ -1055,6 +1112,191 @@ which is the view itself or a :term:`dotted Python name` to such an object.
 All other arguments are optional.  See
 :meth:`pyramid.config.Configurator.add_view` for more information.
 
+.. _using_add_handler:
+
+Using :meth:`~pyramid.config.Configurator.add_handler` to Register a Handler
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The :meth:`pyramid.config.Configurator.add_handler` method will scan a
+:term:`view handler` class and automatically set up view configurations for
+its methods that represent "auto-exposed" view callable, or those that were
+decorated explicitly with the :class:`~pyramid.view.action` decorator. This
+decorator is used to setup additional view configuration information for
+individual methods of the class, and can be used repeatedly for a single view
+method to register multiple view configurations for it.
+
+.. code-block:: python
+    :linenos:
+
+    from myapp.handlers import Hello
+    config.add_handler('hello', '/hello/{action}', handler=Hello)
+
+This example will result in a route being added for the pattern
+``/hello/{action}``, each method of the ``Hello`` class will then be examined
+to register the views. The value of ``{action}`` in the route pattern will be
+used to determine which view should be called, and each view in the class
+will be setup with a view predicate that requires a specific ``action`` name.
+
+If the URL in the above example was ``/hello/index``, then the ``index``
+method of the Hello class would be called.
+
+Alternatively, the action can be declared specifically for a URL to go to a
+specific ``action`` name:
+
+.. code-block:: python
+    :linenos:
+    
+    from myapp.handlers import Hello
+    config.add_handler('hello_index', '/hello/index', 
+                       handler=Hello, action='index')
+
+This will result one of the methods that are configured for the ``action`` of
+'index' in the ``Hello`` handler class to be called. In this case the name of
+the method is the same as the action name: 'index'. However, this need not be
+the case, as we will see below.
+
+When calling :meth:`~pyramid.config.Configurator.add_handler`, an ``action``
+is required in either the route pattern or as a keyword argument, but
+**cannot appear in both places**. A ``handler`` argument must also be
+supplied, which can be either a :term:`asset specification` or a Python
+reference to the handler class. Additional keyword arguments are passed
+directly through to :meth:`pyramid.config.Configurator.add_route`.
+
+For example:
+
+.. code-block:: python
+    :linenos:
+    
+    config.add_handler('hello', '/hello/{action}',
+                       handler='mypackage.handlers.MyHandler')
+
+Multiple :meth:`~pyramid.config.Configurator.add_handler` calls can specify
+the same handler, to register specific route names for different
+handler/action combinations. For example:
+
+.. code-block:: python
+    :linenos:
+    
+    config.add_handler('hello_index', '/hello/index', 
+                       handler=Hello, action='index')
+    config.add_handler('bye_index', '/hello/bye', 
+                       handler=Hello, action='bye')
+
+.. note::
+
+  Handler configuration may also be added to the system via :term:`ZCML` (see
+  :ref:`zcml_handler_configuration`).
+
+View Setup in the Handler Class
++++++++++++++++++++++++++++++++
+
+The handler class specified can have a single class level attribute called
+``__autoexpose__`` which should be a regular expression or the value
+``None``. It's used to determine which method names will result in additional
+view configurations being registered.
+
+When :meth:`~pyramid.config.Configurator.add_handler` runs, every
+method in the handler class will be searched and a view registered if the
+method name matches the ``__autoexpose__`` regular expression, or if the
+method was decorated with :class:`~pyramid.view.action`.
+
+Every method in the handler class that has a name meeting the
+``_autoexpose__`` regular expression will have a view registered for an
+``action`` name corresponding to the method name. This functionality can be
+disabled by setting the ``__autoexpose__`` attribute to ``None``:
+
+.. code-block:: python
+    :linenos:
+
+    from pyramid.view 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 {}
+
+With auto-expose effectively disabled, no views will be registered for a
+method unless it is specifically decorated with :class:`~pyramid.view.action`.
+
+Action Decorators in a Handler
+++++++++++++++++++++++++++++++
+
+The :class:`~pyramid.view.action` decorator registers view configuration
+information on the handler method, which is used by
+:meth:`~pyramid.config.Configurator.add_handler` to setup the view
+configuration.
+
+All keyword arguments are recorded, and passed to
+:meth:`~pyramid.config.Configurator.add_view`. Any valid keyword arguments
+for :meth:`~pyramid.config.Configurator.add_view` can thus be used with the
+:class:`~pyramid.view.action` decorator to further restrict when the view
+will be called.
+
+One important difference is that a handler method can respond to an
+``action`` name that is different from the method name by passing in a
+``name`` argument.
+
+Example:
+
+.. code-block:: python
+    :linenos:
+    
+    from pyramid.view import action
+   
+    class Hello(object):
+        def __init__(self, request):
+            self.request = request
+        
+        @action(name='index', renderer='created.mak', request_method='POST')
+        def create(self):
+            return {}
+
+        @action(renderer="view_all.mak", request_method='GET')
+        def index(self):
+            return {}
+
+This will register two views that require the ``action`` to be ``index``,
+with the additional view predicate requiring a specific request method.
+
+It can be useful to decorate a single method multiple times with
+:class:`~pyramid.view.action`. Each action decorator will register a new view
+for the method. By specifying different names and renderers for each action,
+the same view logic can be exposed and rendered differently on multiple URLs.
+
+Example:
+
+.. code-block:: python
+    :linenos:
+    
+    from pyramid.view import action
+   
+    class Hello(object):
+        def __init__(self, request):
+            self.request = request
+        
+        @action(name='home', renderer='home.mak')
+        @action(name='about', renderer='about.mak')
+        def show_template(self):
+            # prep some template vars
+            return {}
+
+    # in the config
+    config.add_handler('hello', '/hello/{action}', handler=Hello)
+
+With this configuration, the url ``/hello/home`` will find a view
+configuration that results in calling the ``show_template`` method, then
+rendering the template with ``home.mak``, and the url ``/hello/about`` will
+call the same method and render the ``about.mak`` template.
+
 .. index::
    single: resource interfaces