First filter attempt

managers.py

@@ -1,4 +1,58 @@
 from django.db import models
 
 class EntityManager(models.Manager):
-    pass
+    def filter(self, *args, **kwargs):
+        qs = self.get_query_set().filter(*args)
+        for lookup, value in kwargs.items():
+            lookups = self._filter_by_lookup(qs, lookup, value)
+            qs = qs.filter(**lookups)
+        return qs
+
+    def _filter_by_lookup(self, qs, lookup, value):
+        eav_entity = self._get_eav_entity()
+        slugs = eav_entity.get_all_attribute_slugs()
+        cache = eav_entity.get_attr_cache()
+        fields = self.model._meta.get_all_field_names()
+        attributes = eav_entity.get_all_attributes()
+
+        config_cls = self._get_config_cls()
+        eav_prefix = config_cls.proxy_field_name
+        gr_name = config_cls.generic_relation_field_name
+
+        if not lookup.startswith("%s__" % eav_prefix):
+            return {lookup: value}
+
+        lookup = lookup.lstrip("%s__" % eav_prefix)        
+
+        # Sublookup will be None if there is no __ in the lookup
+        name, sublookup = (lookup.split('__', 1) + [None])[:2]
+
+        if name in slugs:
+            # EAV attribute (Attr instance linked to entity)
+            attribute = eav_entity.get_attribute_by_slug(name)
+            return self._filter_by_simple_schema(qs, lookup, sublookup, value, attribute)
+        else:
+            raise NameError('Cannot filter items by attributes: unknown '
+                            'attribute "%s". Available fields: %s. '
+                            'Available attribute: %s.' % (name,
+                            ', '.join(fields), ', '.join(slugs)))
+
+    def _filter_by_simple_schema(self, qs, lookup, sublookup, value, attribute):
+        config_cls = self._get_config_cls()
+        eav_prefix = config_cls.proxy_field_name
+        gr_name = config_cls.generic_relation_field_name
+          
+
+        value_lookup = '%s__value_%s' % (gr_name, attribute.datatype)
+        if sublookup:
+            value_lookup = '%s__%s' % (value_lookup, sublookup)
+        return { value_lookup: value }
+
+    def _get_config_cls(self):
+        from .utils import EavRegistry
+        return EavRegistry.get_config_cls_for_model(self.model)
+
+    def _get_eav_entity(self):
+        cls = self._get_config_cls()
+        eav_entity_name = cls.proxy_field_name
+        return getattr(self.model, eav_entity_name)

utils.py

@@ -24,6 +24,10 @@ class EavRegistry(object):
     """
     cache = {}
 
+    @staticmethod
+    def get_config_cls_for_model(model_cls):
+        return EavRegistry.cache[model_cls.__name__]['config_cls']
+
     @staticmethod
     def attach(sender, *args, **kwargs):
         """