Removed use of _get_subclasses favouring get_document

_get_subclasses not actually required and causes issues
where Base Classes aren't imported but dont actually
need to be.

Fixes #271

AUTHORS

@@ -79,3 +79,4 @@ that much better:
  * Alice Zoë Bevan-McGregor
  * Stephen Young
  * tkloc
+ * aid

docs/changelog.rst

@@ -5,6 +5,8 @@ Changelog
 Changes in dev
 ==============
 
+- Removed Document._get_subclasses() - no longer required
+- Fixed bug requiring subclasses when not actually needed
 - Fixed deletion of dynamic data
 - Added support for the $elementMatch operator
 - Added reverse option to SortedListFields

docs/upgrade.rst

@@ -8,6 +8,8 @@ Upgrading
 Embedded Documents - if you had a `pk` field you will have to rename it from `_id`
 to `pk` as pk is no longer a property of Embedded Documents.
 
+Document._get_subclasses - Is no longer used and the class method has been removed.
+
 0.4 to 0.5
 ===========
 

mongoengine/base.py

@@ -845,21 +845,6 @@ class BaseDocument(object):
         """
         return cls._meta.get('collection', None)
 
-    @classmethod
-    def _get_subclasses(cls):
-        """Return a dictionary of all subclasses (found recursively).
-        """
-        try:
-            subclasses = cls.__subclasses__()
-        except:
-            subclasses = cls.__subclasses__(cls)
-
-        all_subclasses = {}
-        for subclass in subclasses:
-            all_subclasses[subclass._class_name] = subclass
-            all_subclasses.update(subclass._get_subclasses())
-        return all_subclasses
-
     @classmethod
     def _from_son(cls, son):
         """Create an instance of a Document (subclass) from a PyMongo SON.
@@ -877,16 +862,7 @@ class BaseDocument(object):
 
         # Return correct subclass for document type
         if class_name != cls._class_name:
-            subclasses = cls._get_subclasses()
+            cls = get_document(class_name)
-            if class_name not in subclasses:
-                # Type of document is probably more generic than the class
-                # that has been queried to return this SON
-                raise NotRegistered("""
-                        `%s` has not been registered in the document registry.
-                        Importing the document class automatically registers it,
-                        has it been imported?
-                    """.strip() % class_name)
-            cls = subclasses[class_name]
 
         changed_fields = []
         for field_name, field in cls._fields.items():

mongoengine/document.py

@@ -162,11 +162,10 @@ class Document(BaseDocument):
 
         doc = self.to_mongo()
 
-        created = '_id' in doc
+        created = force_insert or '_id' not in doc
-        creation_mode = force_insert or not created
         try:
             collection = self.__class__.objects._collection
-            if creation_mode:
+            if created:
                 if force_insert:
                     object_id = collection.insert(doc, safe=safe, **write_options)
                 else:
@@ -194,7 +193,7 @@ class Document(BaseDocument):
         self[id_field] = self._fields[id_field].to_python(object_id)
 
         self._changed_fields = []
-        signals.post_save.send(self.__class__, document=self, created=creation_mode)
+        signals.post_save.send(self.__class__, document=self, created=created)
 
     def cascade_save(self, *args, **kwargs):
         """Recursively saves any references / generic references on an object"""

tests/document.py

@@ -158,29 +158,6 @@ class DocumentTest(unittest.TestCase):
         }
         self.assertEqual(Dog._superclasses, dog_superclasses)
 
-    def test_get_subclasses(self):
-        """Ensure that the correct list of subclasses is retrieved by the
-        _get_subclasses method.
-        """
-        class Animal(Document): pass
-        class Fish(Animal): pass
-        class Mammal(Animal): pass
-        class Human(Mammal): pass
-        class Dog(Mammal): pass
-
-        mammal_subclasses = {
-            'Animal.Mammal.Dog': Dog,
-            'Animal.Mammal.Human': Human
-        }
-        self.assertEqual(Mammal._get_subclasses(), mammal_subclasses)
-
-        animal_subclasses = {
-            'Animal.Fish': Fish,
-            'Animal.Mammal': Mammal,
-            'Animal.Mammal.Dog': Dog,
-            'Animal.Mammal.Human': Human
-        }
-        self.assertEqual(Animal._get_subclasses(), animal_subclasses)
 
     def test_external_super_and_sub_classes(self):
         """Ensure that the correct list of sub and super classes is assembled.
@@ -202,20 +179,6 @@ class DocumentTest(unittest.TestCase):
         }
         self.assertEqual(Dog._superclasses, dog_superclasses)
 
-        animal_subclasses = {
-            'Base.Animal.Fish': Fish,
-            'Base.Animal.Mammal': Mammal,
-            'Base.Animal.Mammal.Dog': Dog,
-            'Base.Animal.Mammal.Human': Human
-        }
-        self.assertEqual(Animal._get_subclasses(), animal_subclasses)
-
-        mammal_subclasses = {
-            'Base.Animal.Mammal.Dog': Dog,
-            'Base.Animal.Mammal.Human': Human
-        }
-        self.assertEqual(Mammal._get_subclasses(), mammal_subclasses)
-
         Base.drop_collection()
 
         h = Human()
@@ -1014,10 +977,8 @@ class DocumentTest(unittest.TestCase):
 
         # Mimic Place and NicePlace definitions being in a different file
         # and the NicePlace model not being imported in at query time.
-        @classmethod
+        from mongoengine.base import _document_registry
-        def _get_subclasses(cls):
+        del(_document_registry['Place.NicePlace'])
-            return {}
-        Place._get_subclasses = _get_subclasses
 
         def query_without_importing_nice_place():
             print Place.objects.all()