Fixed #925 -- Added TEMPLATE_CONTEXT_PROCESSORS, which lets you specify processesors for DjangoContext. Thanks, Luke Plant

git-svn-id: http://code.djangoproject.com/svn/django/trunk@1773 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/conf/global_settings.py

@@ -100,6 +100,15 @@ TEMPLATE_LOADERS = (
 #     'django.core.template.loaders.eggs.load_template_source',
 )
 
+# List of processors used by DjangoContext to populate the context.
+# Each one should be a callable that takes the request object as its
+# only parameter and returns a dictionary to add to the context.
+TEMPLATE_CONTEXT_PROCESSORS = (
+    'django.core.context_processors.auth',
+    'django.core.context_processors.debug',
+    'django.core.context_processors.i18n',
+)
+
 # URL prefix for admin media -- CSS, JavaScript and images. Make sure to use a
 # trailing slash.
 # Examples: "http://foo.com/media/", "/media/".

django/core/extensions.py

@@ -2,11 +2,34 @@
 # of MVC. In other words, these functions/classes introduce controlled coupling
 # for convenience's sake.
 
-from django.core.exceptions import Http404, ObjectDoesNotExist
+from django.core.exceptions import Http404, ImproperlyConfigured, ObjectDoesNotExist
 from django.core.template import Context, loader
-from django.conf.settings import DEBUG, INTERNAL_IPS
+from django.conf.settings import TEMPLATE_CONTEXT_PROCESSORS
 from django.utils.httpwrappers import HttpResponse
 
+_standard_context_processors = None
+
+# This is a function rather than module-level procedural code because we only
+# want it to execute if somebody uses DjangoContext.
+def get_standard_processors():
+    global _standard_context_processors
+    if _standard_context_processors is None:
+        processors = []
+        for path in TEMPLATE_CONTEXT_PROCESSORS:
+            i = path.rfind('.')
+            module, attr = path[:i], path[i+1:]
+            try:
+                mod = __import__(module, '', '', [attr])
+            except ImportError, e:
+                raise ImproperlyConfigured, 'Error importing request processor module %s: "%s"' % (module, e)
+            try:
+                func = getattr(mod, attr)
+            except AttributeError:
+                raise ImproperlyConfigured, 'Module "%s" does not define a "%s" callable request processor' % (module, attr)
+            processors.append(func)
+        _standard_context_processors = tuple(processors)
+    return _standard_context_processors
+
 def render_to_response(*args, **kwargs):
     return HttpResponse(loader.render_to_string(*args, **kwargs))
 load_and_render = render_to_response # For backwards compatibility.
@@ -25,24 +48,19 @@ def get_list_or_404(mod, **kwargs):
 
 class DjangoContext(Context):
     """
-    This subclass of template.Context automatically populates 'user' and
+    This subclass of template.Context automatically populates itself using
-    'messages' in the context.
+    the processors defined in TEMPLATE_CONTEXT_PROCESSORS.
+    Additional processors can be specified as a list of callables
+    using the "processors" keyword argument.
     """
-    def __init__(self, request, dict=None):
+    def __init__(self, request, dict=None, processors=None):
         Context.__init__(self, dict)
-        self['user'] = request.user
+        if processors is None:
-        self['messages'] = request.user.get_and_delete_messages()
+            processors = ()
-        self['perms'] = PermWrapper(request.user)
-        from django.conf import settings
-        self['LANGUAGES'] = settings.LANGUAGES
-        if hasattr(request, 'LANGUAGE_CODE'):
-            self['LANGUAGE_CODE'] = request.LANGUAGE_CODE
         else:
-            self['LANGUAGE_CODE'] = settings.LANGUAGE_CODE
+            processors = tuple(processors)
-        if DEBUG and request.META.get('REMOTE_ADDR') in INTERNAL_IPS:
+        for processor in get_standard_processors() + processors:
-            self['debug'] = True
+            self.update(processor(request))
-            from django.core import db
-            self['sql_queries'] = db.db.queries
 
 # PermWrapper and PermLookupDict proxy the permissions system into objects that
 # the template system can understand.

django/views/generic/create_update.py

@@ -3,14 +3,14 @@ from django.core.xheaders import populate_xheaders
 from django.core.template import loader
 from django.core import formfields, meta
 from django.views.auth.login import redirect_to_login
-from django.core.extensions import DjangoContext as Context
+from django.core.extensions import DjangoContext
 from django.core.paginator import ObjectPaginator, InvalidPage
 from django.utils.httpwrappers import HttpResponse, HttpResponseRedirect
 from django.core.exceptions import Http404, ObjectDoesNotExist, ImproperlyConfigured
 
 def create_object(request, app_label, module_name, template_name=None,
-                 template_loader=loader, extra_context={},
+        template_loader=loader, extra_context={}, post_save_redirect=None,
-                 post_save_redirect=None, login_required=False, follow=None):
+        login_required=False, follow=None, context_processors=None):
     """
     Generic object-creation function.
 
@@ -60,9 +60,9 @@ def create_object(request, app_label, module_name, template_name=None,
     if not template_name:
         template_name = "%s/%s_form" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
-        'form' : form,
+        'form': form,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -71,9 +71,9 @@ def create_object(request, app_label, module_name, template_name=None,
     return HttpResponse(t.render(c))
 
 def update_object(request, app_label, module_name, object_id=None, slug=None,
-                  slug_field=None, template_name=None, template_loader=loader,
+        slug_field=None, template_name=None, template_loader=loader,
-                  extra_lookup_kwargs={}, extra_context={}, post_save_redirect=None,
+        extra_lookup_kwargs={}, extra_context={}, post_save_redirect=None,
-                  login_required=False, follow=None):
+        login_required=False, follow=None, context_processors=None):
     """
     Generic object-update function.
 
@@ -131,10 +131,10 @@ def update_object(request, app_label, module_name, object_id=None, slug=None,
     if not template_name:
         template_name = "%s/%s_form" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
-        'form' : form,
+        'form': form,
-        'object' : object,
+        'object': object,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -145,9 +145,9 @@ def update_object(request, app_label, module_name, object_id=None, slug=None,
     return response
 
 def delete_object(request, app_label, module_name, post_delete_redirect,
-                  object_id=None, slug=None, slug_field=None, template_name=None,
+        object_id=None, slug=None, slug_field=None, template_name=None,
-                  template_loader=loader, extra_lookup_kwargs={},
+        template_loader=loader, extra_lookup_kwargs={}, extra_context={},
-                  extra_context={}, login_required=False):
+        login_required=False, context_processors=None):
     """
     Generic object-delete function.
 
@@ -188,9 +188,9 @@ def delete_object(request, app_label, module_name, post_delete_redirect,
         if not template_name:
             template_name = "%s/%s_confirm_delete" % (app_label, module_name)
         t = template_loader.get_template(template_name)
-        c = Context(request, {
+        c = DjangoContext(request, {
-            'object' : object,
+            'object': object,
-        })
+        }, context_processors)
         for key, value in extra_context.items():
             if callable(value):
                 c[key] = value()
@@ -199,4 +199,3 @@ def delete_object(request, app_label, module_name, post_delete_redirect,
         response = HttpResponse(t.render(c))
         populate_xheaders(request, response, app_label, module_name, getattr(object, object._meta.pk.name))
         return response
-

django/views/generic/date_based.py

@@ -1,14 +1,14 @@
 from django.core.template import loader
 from django.core.exceptions import Http404, ObjectDoesNotExist
-from django.core.extensions import DjangoContext as Context
+from django.core.extensions import DjangoContext
 from django.core.xheaders import populate_xheaders
 from django.models import get_module
 from django.utils.httpwrappers import HttpResponse
 import datetime, time
 
 def archive_index(request, app_label, module_name, date_field, num_latest=15,
-                  template_name=None, template_loader=loader,
+        template_name=None, template_loader=loader, extra_lookup_kwargs={},
-                  extra_lookup_kwargs={}, extra_context={}, allow_empty=False):
+        extra_context={}, allow_empty=False, context_processors=None):
     """
     Generic top-level archive of date-based objects.
 
@@ -38,10 +38,10 @@ def archive_index(request, app_label, module_name, date_field, num_latest=15,
     if not template_name:
         template_name = "%s/%s_archive" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'date_list' : date_list,
         'latest' : latest,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -50,8 +50,8 @@ def archive_index(request, app_label, module_name, date_field, num_latest=15,
     return HttpResponse(t.render(c))
 
 def archive_year(request, year, app_label, module_name, date_field,
-                 template_name=None, template_loader=loader,
+        template_name=None, template_loader=loader, extra_lookup_kwargs={},
-                 extra_lookup_kwargs={}, extra_context={}):
+        extra_context={}, context_processors=None):
     """
     Generic yearly archive view.
 
@@ -75,10 +75,10 @@ def archive_year(request, year, app_label, module_name, date_field,
     if not template_name:
         template_name = "%s/%s_archive_year" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'date_list': date_list,
         'year': year,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -87,8 +87,8 @@ def archive_year(request, year, app_label, module_name, date_field,
     return HttpResponse(t.render(c))
 
 def archive_month(request, year, month, app_label, module_name, date_field,
-                  month_format='%b', template_name=None, template_loader=loader,
+        month_format='%b', template_name=None, template_loader=loader,
-                  extra_lookup_kwargs={}, extra_context={}):
+        extra_lookup_kwargs={}, extra_context={}, context_processors=None):
     """
     Generic monthly archive view.
 
@@ -123,10 +123,10 @@ def archive_month(request, year, month, app_label, module_name, date_field,
     if not template_name:
         template_name = "%s/%s_archive_month" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'object_list': object_list,
         'month': date,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -135,9 +135,9 @@ def archive_month(request, year, month, app_label, module_name, date_field,
     return HttpResponse(t.render(c))
 
 def archive_day(request, year, month, day, app_label, module_name, date_field,
-                month_format='%b', day_format='%d', template_name=None,
+        month_format='%b', day_format='%d', template_name=None,
-                template_loader=loader, extra_lookup_kwargs={},
+        template_loader=loader, extra_lookup_kwargs={}, extra_context={},
-                extra_context={}, allow_empty=False):
+        allow_empty=False, context_processors=None):
     """
     Generic daily archive view.
 
@@ -172,12 +172,12 @@ def archive_day(request, year, month, day, app_label, module_name, date_field,
     if not template_name:
         template_name = "%s/%s_archive_day" % (app_label, module_name)
     t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'object_list': object_list,
         'day': date,
         'previous_day': date - datetime.timedelta(days=1),
         'next_day': (date < datetime.date.today()) and (date + datetime.timedelta(days=1)) or None,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()
@@ -198,10 +198,10 @@ def archive_today(request, **kwargs):
     return archive_day(request, **kwargs)
 
 def object_detail(request, year, month, day, app_label, module_name, date_field,
-                  month_format='%b', day_format='%d', object_id=None, slug=None,
+        month_format='%b', day_format='%d', object_id=None, slug=None,
-                  slug_field=None, template_name=None, template_name_field=None,
+        slug_field=None, template_name=None, template_name_field=None,
-                  template_loader=loader, extra_lookup_kwargs={},
+        template_loader=loader, extra_lookup_kwargs={}, extra_context={},
-                  extra_context={}):
+        context_processors=None):
     """
     Generic detail view from year/month/day/slug or year/month/day/id structure.
 
@@ -241,9 +241,9 @@ def object_detail(request, year, month, day, app_label, module_name, date_field,
         t = template_loader.select_template(template_name_list)
     else:
         t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'object': object,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()

django/views/generic/list_detail.py

@@ -2,13 +2,13 @@ from django import models
 from django.core.template import loader
 from django.utils.httpwrappers import HttpResponse
 from django.core.xheaders import populate_xheaders
-from django.core.extensions import DjangoContext as Context
+from django.core.extensions import DjangoContext
 from django.core.paginator import ObjectPaginator, InvalidPage
 from django.core.exceptions import Http404, ObjectDoesNotExist
 
 def object_list(request, app_label, module_name, paginate_by=None, allow_empty=False,
-                template_name=None, template_loader=loader,
+        template_name=None, template_loader=loader, extra_lookup_kwargs={},
-                extra_lookup_kwargs={}, extra_context={}):
+        extra_context={}, context_processors=None):
     """
     Generic list of objects.
 
@@ -48,7 +48,7 @@ def object_list(request, app_label, module_name, paginate_by=None, allow_empty=F
             else:
                 raise Http404
         page = int(page)
-        c = Context(request, {
+        c = DjangoContext(request, {
             'object_list': object_list,
             'is_paginated': paginator.pages > 1,
             'results_per_page': paginate_by,
@@ -59,13 +59,13 @@ def object_list(request, app_label, module_name, paginate_by=None, allow_empty=F
             'previous': page - 1,
             'pages': paginator.pages,
             'hits' : paginator.hits,
-        })
+        }, context_processors)
     else:
         object_list = mod.get_list(**lookup_kwargs)
-        c = Context(request, {
+        c = DjangoContext(request, {
             'object_list': object_list,
             'is_paginated': False
-        })
+        }, context_processors)
         if len(object_list) == 0 and not allow_empty:
             raise Http404
     for key, value in extra_context.items():
@@ -79,9 +79,9 @@ def object_list(request, app_label, module_name, paginate_by=None, allow_empty=F
     return HttpResponse(t.render(c))
 
 def object_detail(request, app_label, module_name, object_id=None, slug=None,
-                  slug_field=None, template_name=None, template_name_field=None,
+        slug_field=None, template_name=None, template_name_field=None,
-                  template_loader=loader, extra_lookup_kwargs={},
+        template_loader=loader, extra_lookup_kwargs={}, extra_context={},
-                  extra_context={}):
+        context_processors=None):
     """
     Generic list of objects.
 
@@ -110,9 +110,9 @@ def object_detail(request, app_label, module_name, object_id=None, slug=None,
         t = template_loader.select_template(template_name_list)
     else:
         t = template_loader.get_template(template_name)
-    c = Context(request, {
+    c = DjangoContext(request, {
         'object': object,
-    })
+    }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
             c[key] = value()

docs/authentication.txt

@@ -438,6 +438,15 @@ Authentication data in templates
 The currently logged-in user and his/her permissions are made available in the
 `template context`_ when you use ``DjangoContext``.
 
+.. admonition:: Technicality
+
+   Technically, these variables are only made available in the template context
+   if you use ``DjangoContext`` *and* your ``TEMPLATE_CONTEXT_PROCESSORS``
+   setting contains ``"django.core.context_processors.auth"``, which is default.
+   For more, see the `DjangoContext docs`_.
+
+   .. _DjangoContext docs: http://www.djangoproject.com/documentation/templates_python/#subclassing-context-djangocontext
+
 Users
 -----
 
@@ -454,7 +463,7 @@ Permissions
 -----------
 
 The currently logged-in user's permissions are stored in the template variable
-``{{ perms }}``. This is an instance of ``django.core.extensions.PermWrapper``,
+``{{ perms }}``. This is an instance of ``django.core.context_processors.PermWrapper``,
 which is a template-friendly proxy of permissions.
 
 In the ``{{ perms }}`` object, single-attribute lookup is a proxy to

docs/generic_views.txt

@@ -128,9 +128,14 @@ arguments:
 
     ``extra_context``        A dictionary of extra data to put into the
                              template's context.
+
+    ``processors``           **New in Django development version.** A tuple of
+                             processors to apply to the ``DjangoContext`` of
+                             this view's template. See the `DjangoContext docs`_
     =======================  ==================================================
 
-.. _`database API docs`: http://www.djangoproject.com/documentation/db_api/
+.. _database API docs: http://www.djangoproject.com/documentation/db_api/
+.. _DjangoContext docs: http://www.djangoproject.com/documentation/templates_python/#subclassing-context-djangocontext
 
 The date-based generic functions are:
 
@@ -247,7 +252,7 @@ The list-detail generic-view framework (in the
 except the former simply has two views: a list of objects and an individual
 object page.
 
-All these views take the same three optional arguments as the date-based ones
+All these views take the same four optional arguments as the date-based ones
 -- and, clearly, they don't accept the ``date_field`` argument.
 
 Individual views are:
@@ -371,4 +376,3 @@ The create/update/delete views are:
 
         object
             The object about to be deleted
-

docs/settings.txt

@@ -547,6 +547,21 @@ The ID, as an integer, of the current site in the ``sites`` database. This is
 used so that application data can hook into specific site(s) and a single
 database can manage content for multiple sites.
 
+TEMPLATE_CONTEXT_PROCESSORS
+---------------------------
+
+Default::
+
+    ("django.core.context_processors.auth",
+    "django.core.context_processors.debug",
+    "django.core.context_processors.i18n")
+
+**Only available in Django development version.**
+
+A tuple of callables that are used to populate the context in ``DjangoContext``.
+These callables take a request object as their argument and return a dictionary
+of items to be merged into the context.
+
 TEMPLATE_DEBUG
 --------------
 

docs/templates_python.txt

@@ -240,21 +240,77 @@ Subclassing Context: DjangoContext
 
 Django comes with a special ``Context`` class,
 ``django.core.extensions.DjangoContext``, that acts slightly differently than
-the normal ``django.core.template.Context``. It takes an ``HttpRequest`` object
+the normal ``django.core.template.Context``. The first difference is that takes
-as its first argument, and it automatically populates the context with a few
+an `HttpRequest object`_ as its first argument. For example::
-variables:
+
+    c = DjangoContext(request, {
+        'foo': 'bar',
+    }
+
+The second difference is that it automatically populates the context with a few
+variables, according to your `TEMPLATE_CONTEXT_PROCESSORS setting`_.
+
+The ``TEMPLATE_CONTEXT_PROCESSORS`` setting is a tuple of callables that take a
+request object as their argument and return a dictionary of items to be merged
+into the context. By default, ``TEMPLATE_CONTEXT_PROCESSORS`` is set to::
+
+    ("django.core.context_processors.auth",
+    "django.core.context_processors.debug",
+    "django.core.context_processors.i18n")
+
+Each processor is applied in order. That means, if one processor adds a
+variable to the context and a second processor adds a variable with the same
+name, the second will override the first. The default processors are explained
+below.
+
+Also, you can give ``DjangoContext`` a list of additional processors, using the
+optional, third positional argument, ``processors``. In this example, the
+``DjangoContext`` instance gets a ``ip_address`` variable::
+
+    def ip_address_processor(request):
+        return {'ip_address': request.META['REMOTE_ADDR']}
+
+    def some_view(request):
+        # ...
+        return DjangoContext({
+            'foo': 'bar',
+        }, [ip_address_processor])
+
+Note: The concept of template-context processors is new in the Django
+development version. In Django 0.90, ``DjangoContext`` automatically populates
+the context with all of the values explained below, but it's not possible to
+add and remove processors.
+
+Here's what each of the default processors does:
+
+.. _HttpRequest object: http://www.djangoproject.com/documentation/request_response/#httprequest-objects
+.. _TEMPLATE_CONTEXT_PROCESSORS setting: http://www.djangoproject.com/documentation/settings/#template-context_processors
+
+django.core.context_processors.auth
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If ``TEMPLATE_CONTEXT_PROCESSORS`` contains this processor, every
+``DjangoContext`` will contain these three variables:
 
     * ``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`` -- A list of ``auth.Message`` objects for the currently
       logged-in user.
-    * ``perms`` -- An instance of ``django.core.extensions.PermWrapper``,
+    * ``perms`` -- An instance of ``django.core.context_processors.PermWrapper``,
       representing the permissions that the currently logged-in user has. See
       the `permissions docs`_.
 
-Also, if your ``DEBUG`` setting is set to ``True``, every ``DjangoContext``
+.. _user authentication docs: http://www.djangoproject.com/documentation/models/authentication/#users
-instance has the following two extra variables:
+.. _permissions docs: http://www.djangoproject.com/documentation/models/authentication/#permissions
+
+django.core.context_processors.debug
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If ``TEMPLATE_CONTEXT_PROCESSORS`` contains this processor, every
+``DjangoContext`` will contain these two variables -- but only if your
+``DEBUG`` setting is set to ``True`` and the request's IP address
+(``request.META['REMOTE_ADDR']``) is in the ``INTERNAL_IPS`` setting:
 
     * ``debug`` -- ``True``. You can use this in templates to test whether
       you're in ``DEBUG`` mode.
@@ -262,6 +318,25 @@ instance has the following two extra variables:
       representing every SQL query that has happened so far during the request
       and how long it took. The list is in order by query.
 
+django.core.context_processors.i18n
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If ``TEMPLATE_CONTEXT_PROCESSORS`` contains this processor, every
+``DjangoContext`` will contain these two variables:
+
+    * ``LANGUAGES`` -- The value of the `LANGUAGES setting`_.
+    * ``LANGUAGE_CODE`` -- ``request.LANGUAGE_CODE``, if it exists. Otherwise,
+      the value of the `LANGUAGE_CODE setting`_.
+
+See the `internationalization docs`_ for more.
+
+.. _LANGUAGES setting: http://www.djangoproject.com/documentation/settings/#languages
+.. _LANGUAGE_CODE setting: http://www.djangoproject.com/documentation/settings/#language-code
+.. _internationalization docs: http://www.djangoproject.com/documentation/i18n/
+
+Subclassing Context: Custom subclasses
+--------------------------------------
+
 Feel free to subclass ``Context`` yourself if you find yourself wanting to give
 each template something "automatically." For instance, if you want to give
 every template automatic access to the current time, use something like this::
@@ -281,9 +356,6 @@ This technique has two caveats:
     * You'll have to be careful not to set the variable ``current_time`` when
       you populate this context. If you do, you'll override the other one.
 
-.. _user authentication docs: http://www.djangoproject.com/documentation/models/authentication/#users
-.. _permissions docs: http://www.djangoproject.com/documentation/models/authentication/#permissions
-
 Loading templates
 -----------------