Fixed #13348: Restored ability to load models from apps in eggs. Thanks Ramiro and metzen for pointers on how to find out if a module loaded from an egg has a particular submodule.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12982 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 27 insertions, 0 deletions

diff --git a/django/utils/module_loading.py b/django/utils/module_loading.py
new file mode 100644
index 0000000000..b23336e9df
--- /dev/null
+++ b/django/utils/module_loading.py
@@ -0,0 +1,27 @@
+import os
+import imp
+
+def module_has_submodule(mod, submod_name):
+    # If the module was loaded from an egg, __loader__ will be set and 
+    # its find_module must be used to search for submodules.
+    loader = getattr(mod, '__loader__', None)
+    if loader:
+        mod_path = "%s.%s" % (mod.__name__, submod_name)
+        mod_path = mod_path[len(loader.prefix):]
+        x = loader.find_module(mod_path)
+        if x is None:
+            # zipimport.zipimporter.find_module is documented to take
+            # dotted paths but in fact through Pyton 2.7 is observed 
+            # to require os.sep in place of dots...so try using os.sep
+            # if the dotted path version failed to find the requested 
+            # submodule.
+            x = loader.find_module(mod_path.replace('.', os.sep))
+        return x is not None
+
+    try:
+        imp.find_module(submod_name, mod.__path__)
+        return True
+    except ImportError:
+        return False
+
+