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/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
-    'messages' in the context.
+    This subclass of template.Context automatically populates itself using
+    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
-        self['messages'] = request.user.get_and_delete_messages()
-        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
+        if processors is None:
+            processors = ()
         else:
-            self['LANGUAGE_CODE'] = settings.LANGUAGE_CODE
-        if DEBUG and request.META.get('REMOTE_ADDR') in INTERNAL_IPS:
-            self['debug'] = True
-            from django.core import db
-            self['sql_queries'] = db.db.queries
+            processors = tuple(processors)
+        for processor in get_standard_processors() + processors:
+            self.update(processor(request))
 
 # PermWrapper and PermLookupDict proxy the permissions system into objects that
 # the template system can understand.