Model___field notation now automatically chooses correct application + separated translation into own function

.gitignore

@@ -11,4 +11,5 @@ pushhg
 pushreg
 mypoly.py
 tmp
+poly2.py
 

README.rst

@@ -228,12 +228,14 @@ Manager Inheritance
 
 The current polymorphic models implementation unconditionally
 inherits all managers from its base models (but only the
-polymorphic ones). An example::
+polymorphic base models).
+
+An example (inheriting from MyModel above)::
 
     class MyModel2(MyModel):
         pass
 
-    # Managers inherited from MyModel, delivering MyModel2 objects
+    # Managers inherited from MyModel, delivering MyModel2 objects (including MyModel2 subclass objects)
     >>> MyModel2.objects.all()
     >>> MyModel2.ordered_objects.all()
 

poly/polymorphic.py

@@ -743,19 +743,56 @@ def _translate_polymorphic_filter_spec(queryset_model, field_path, field_val):
         return _create_model_filter_Q(field_val, not_instance_of=True)
     elif not '___' in field_path:
         return None #no change
-    
+
     # filter expression contains '___' (i.e. filter for polymorphic field)
     # => get the model class specified in the filter expression
-    # TODO: if app not given, just model name => try to find model in any app??
-    classname, sep, pure_field_path = field_path.partition('___')
-    if '__' in classname: appname, sep, classname = classname.partition('__')
-    else: appname = queryset_model._meta.app_label
-    model = models.get_model(appname, classname)
-    assert model, 'model %s (in app %s) not found!' % (modelname, appname)
-    if not issubclass(model, queryset_model):
-        e = 'queryset filter error: "' + model.__name__ + '" is not derived from "' + queryset_model.__name__ + '"'
-        raise AssertionError(e)
+    newpath = _translate_polymorphic_field_path(queryset_model, field_path)
+    return (newpath, field_val)
+
+
+def _translate_polymorphic_field_path(queryset_model, field_path):
+    """
+    Translate a field path from keyword argument, as used for
+    PolymorphicQuerySet.filter()-like functions (and Q objects).
     
+    E.g.: ModelC___field3 is translated into modela__modelb__modelc__field3
+    Returns: translated path
+    """
+    classname, sep, pure_field_path = field_path.partition('___')
+    assert sep == '___'
+
+    if '__' in classname:
+        # the user has app label prepended to class name via __ => use Django's get_model function
+        appname, sep, classname = classname.partition('__')
+        model = models.get_model(appname, classname)
+        assert model, 'model %s (in app %s) not found!' % (model.__name__, appname)
+        if not issubclass(model, queryset_model):
+            e = 'queryset filter error: "' + model.__name__ + '" is not derived from "' + queryset_model.__name__ + '"'
+            raise AssertionError(e)
+        
+    else:
+        # the user has only given us the class name via __
+        # => select the model from the sub models of the queryset base model
+
+        # function to collect all sub-models, this could be optimized
+        def add_all_sub_models(model, result):
+            if issubclass(model, models.Model) and model != models.Model:
+                # model name is occurring twice in submodel inheritance tree => Error
+                if model.__name__ in result and model!=result[model.__name__]:
+                    assert model, 'model name is ambiguous: %s.%s, %s.%s!' % (
+                        model._meta.app_label, model.__name__,
+                        result[model.__name__]._meta.app_label, result[model.__name__].__name__)
+            
+                result[model.__name__] = model
+
+            for b in model.__subclasses__():
+                add_all_sub_models(b, result)
+        
+        submodels = {}
+        add_all_sub_models(queryset_model, submodels)
+        model=submodels.get(classname,None)
+        assert model, 'model %s not found (not a subclass of %s)!' % (model.__name__, queryset_model.__name__)
+
     # create new field path for expressions, e.g. for baseclass=ModelA, myclass=ModelC
     # 'modelb__modelc" is returned
     def _create_base_path(baseclass, myclass):
@@ -770,7 +807,8 @@ def _translate_polymorphic_filter_spec(queryset_model, field_path, field_val):
     basepath = _create_base_path(queryset_model, model)
     newpath = basepath + '__' if basepath else ''
     newpath += pure_field_path
-    return (newpath, field_val)
+    return newpath
+
 
 def _create_model_filter_Q(modellist, not_instance_of=False):
     """
@@ -1037,4 +1075,3 @@ class PolymorphicModel(models.Model):
             if f != last:  out += ', '
         return '<' + out + '>'
     
-