magic-removal: Django no longer requires a database. Moved database-handling stuff in django handlers to use dispatching

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@1807 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/handlers/base.py

@@ -1,3 +1,5 @@
+from django.core import signals
+from django.dispatch import dispatcher
 from django.utils import httpwrappers
 
 class BaseHandler:
@@ -48,13 +50,9 @@ class BaseHandler:
     def get_response(self, path, request):
         "Returns an HttpResponse object for the given HttpRequest"
         from django.core import exceptions, urlresolvers
-        from django.db import connection, DatabaseError
         from django.core.mail import mail_admins
         from django.conf.settings import DEBUG, INTERNAL_IPS, ROOT_URLCONF
 
-        # Reset query list per request.
-        connection.queries = []
-
         # Apply request middleware
         for middleware_method in self._request_middleware:
             response = middleware_method(request)
@@ -94,22 +92,15 @@ class BaseHandler:
             else:
                 callback, param_dict = resolver.resolve404()
                 return callback(request, **param_dict)
-        except DatabaseError:
-            connection.rollback()
-            if DEBUG:
-                return self.get_technical_error_response(request)
-            else:
-                subject = 'Database error (%s IP): %s' % ((request.META.get('REMOTE_ADDR') in INTERNAL_IPS and 'internal' or 'EXTERNAL'), getattr(request, 'path', ''))
-                message = "%s\n\n%s" % (self._get_traceback(), request)
-                mail_admins(subject, message, fail_silently=True)
-                return self.get_friendly_error_response(request, resolver)
         except exceptions.PermissionDenied:
             return httpwrappers.HttpResponseForbidden('<h1>Permission denied</h1>')
         except: # Handle everything else, including SuspiciousOperation, etc.
             if DEBUG:
                 return self.get_technical_error_response(request)
             else:
-                subject = 'Coding error (%s IP): %s' % ((request.META.get('REMOTE_ADDR') in INTERNAL_IPS and 'internal' or 'EXTERNAL'), getattr(request, 'path', ''))
+                receivers = dispatcher.send(signal=signals.got_request_exception)
+                # When DEBUG is False, send an error message to the admins.
+                subject = 'Error (%s IP): %s' % ((request.META.get('REMOTE_ADDR') in INTERNAL_IPS and 'internal' or 'EXTERNAL'), getattr(request, 'path', ''))
                 try:
                     request_repr = repr(request)
                 except:
@@ -121,7 +112,7 @@ class BaseHandler:
     def get_friendly_error_response(self, request, resolver):
         """
         Returns an HttpResponse that displays a PUBLIC error message for a
-        fundamental database or coding error.
+        fundamental error.
         """
         from django.core import urlresolvers
         callback, param_dict = resolver.resolve500()
@@ -130,7 +121,7 @@ class BaseHandler:
     def get_technical_error_response(self, request, is404=False, exception=None):
         """
         Returns an HttpResponse that displays a TECHNICAL error message for a
-        fundamental database or coding error.
+        fundamental error.
         """
         import sys
         from django.views import debug

django/core/handlers/modpython.py

@@ -1,4 +1,6 @@
 from django.core.handlers.base import BaseHandler
+from django.core import signals
+from django.dispatch import dispatcher
 from django.utils import datastructures, httpwrappers
 from pprint import pformat
 import os
@@ -128,17 +130,17 @@ class ModPythonHandler(BaseHandler):
         # now that the environ works we can see the correct settings, so imports
         # that use settings now can work
         from django.conf import settings
-        from django.db import connection
 
         # if we need to set up middleware, now that settings works we can do it now.
         if self._request_middleware is None:
             self.load_middleware()
 
+        dispatcher.send(signal=signals.request_started)
         try:
             request = ModPythonRequest(req)
             response = self.get_response(req.uri, request)
         finally:
-            connection.close()
+            dispatcher.send(signal=signals.request_finished)
 
         # Apply response middleware
         for middleware_method in self._response_middleware:

django/core/handlers/wsgi.py

@@ -1,4 +1,6 @@
 from django.core.handlers.base import BaseHandler
+from django.core import signals
+from django.dispatch import dispatcher
 from django.utils import datastructures, httpwrappers
 from pprint import pformat
 
@@ -143,18 +145,18 @@ class WSGIRequest(httpwrappers.HttpRequest):
 class WSGIHandler(BaseHandler):
     def __call__(self, environ, start_response):
         from django.conf import settings
-        from django.db import connection
 
         # Set up middleware if needed. We couldn't do this earlier, because
         # settings weren't available.
         if self._request_middleware is None:
             self.load_middleware()
 
+        dispatcher.send(signal=signals.request_started)
         try:
             request = WSGIRequest(environ)
             response = self.get_response(request.path, request)
         finally:
-            connection.close()
+            dispatcher.send(signal=signals.request_finished)
 
         # Apply response middleware
         for middleware_method in self._response_middleware:

django/core/signals.py

@@ -0,0 +1,3 @@
+request_started = object()
+request_finished = object()
+got_request_exception = object()

django/db/__init__.py

@@ -1,4 +1,6 @@
 from django.conf.settings import DATABASE_ENGINE
+from django.core import signals
+from django.dispatch import dispatcher
 
 __all__ = ('backend', 'connection', 'DatabaseError')
 
@@ -23,3 +25,17 @@ get_creation_module = lambda: __import__('django.db.backends.%s.creation' % DATA
 
 connection = backend.DatabaseWrapper()
 DatabaseError = backend.DatabaseError
+
+# Register an event that closes the database connection
+# when a Django request is finished.
+dispatcher.connect(lambda: connection.close(), signal=signals.request_finished)
+
+# Register an event that resets connection.queries
+# when a Django request is started.
+def reset_queries():
+    connection.queries = []
+dispatcher.connect(reset_queries, signal=signals.request_started)
+
+# Register an event that rolls back the connection
+# when a Django request has an exception.
+dispatcher.connect(lambda: connection.rollback(), signal=signals.got_request_exception)