Fixed #8126: improved admin.autodiscover() to be more forgiving of …

…invalid `INSTALLED_APPS` entries and/or exotic import schemes that don't have `__path__`.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8583 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admin/__init__.py

@@ -10,10 +10,31 @@ def autodiscover():
     """
     import imp
     from django.conf import settings
+
     for app in settings.INSTALLED_APPS:
+        # For each app, we need to look for an admin.py inside that app's
+        # package. We can't use os.path here -- recall that modules may be
+        # imported different ways (think zip files) -- so we need to get
+        # the app's __path__ and look for admin.py on that path.
+
+        # Step 1: find out the app's __path__ Import errors here will (and
+        # should) bubble up, but a missing __path__ (which is legal, but weird)
+        # fails silently -- apps that do weird things with __path__ might
+        # need to roll their own admin registration.
+        try:
+            app_path = __import__(app, {}, {}, [app.split('.')[-1]]).__path__
+        except AttributeError:
+            continue
+
+        # Step 2: use imp.find_module to find the app's admin.py. For some
+        # reason imp.find_module raises ImportError if the app can't be found
+        # but doesn't actually try to import the module. So skip this app if
+        # its admin.py doesn't exist
         try:
-            imp.find_module("admin", __import__(app, {}, {}, [app.split(".")[-1]]).__path__)
+            imp.find_module('admin', app_path)
         except ImportError:
-            # there is no app admin.py, skip it
             continue
+
+        # Step 3: import the app's admin file. If this has errors we want them
+        # to bubble up.
         __import__("%s.admin" % app)