sqlalchemy: Merged revisions 3679 to 3723 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/sqlalchemy@3724 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 23 insertions, 10 deletions

diff --git a/docs/templates_python.txt b/docs/templates_python.txt
index 8da589a125..950b122339 100644
--- a/docs/templates_python.txt
+++ b/docs/templates_python.txt
@@ -198,9 +198,19 @@ some things to keep in mind:
 How invalid variables are handled
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-If a variable doesn't exist, the template system inserts the value of the
-``TEMPLATE_STRING_IF_INVALID`` setting, which is set to ``''`` (the empty
-string) by default.
+Generally, if a variable doesn't exist, the template system inserts the
+value of the ``TEMPLATE_STRING_IF_INVALID`` setting, which is set to ``''``
+(the empty string) by default.
+
+Filters that are applied to an invalid variable will only be applied if
+``TEMPLATE_STRING_IF_INVALID`` is set to ``''`` (the empty string). If
+``TEMPLATE_STRING_IF_INVALID`` is set to any other value, variable
+filters will be ignored.
+
+This behavior is slightly different for the ``if``, ``for`` and ``regroup``
+template tags. If an invalid variable is provided to one of these template
+tags, the variable will be interpreted as ``None``. Filters are always
+applied to invalid variables within these template tags.
 
 Playing with Context objects
 ----------------------------
@@ -300,19 +310,22 @@ If ``TEMPLATE_CONTEXT_PROCESSORS`` contains this processor, every
     * ``user`` -- An ``auth.User`` instance representing the currently
       logged-in user (or an ``AnonymousUser`` instance, if the client isn't
       logged in). See the `user authentication docs`.
-      
-    * ``messages`` -- Returns a list of messages for the currently logged-in
-      user (set with ``user.add_message()``). Behind the scenes, this calls
-      ``request.user.get_and_delete_messages()``, which iterates over user's
-      messages and returns the actual message before deleting the ``Message``
-      object.
-      
+
+    * ``messages`` -- A list of messages (as strings) for the currently
+      logged-in user. Behind the scenes, this calls
+      ``request.user.get_and_delete_messages()`` for every request. That method
+      collects the user's messages and deletes them from the database.
+
+      Note that messages are set with ``user.add_message()``. See the
+      `message docs`_ for more.
+
     * ``perms`` -- An instance of
       ``django.core.context_processors.PermWrapper``, representing the
       permissions that the currently logged-in user has. See the `permissions
       docs`_.
 
 .. _user authentication docs: http://www.djangoproject.com/documentation/authentication/#users
+.. _message docs: http://www.djangoproject.com/documentation/authentication/#messages
 .. _permissions docs: http://www.djangoproject.com/documentation/authentication/#permissions
 
 django.core.context_processors.debug