Added support for distinct and db_alias (MongoEngine/mongoengine#59)

AUTHORS

@@ -115,3 +115,4 @@ that much better:
  * Alexandre González
  * Thomas Steinacher
  * Tommi Komulainen
+ * Peter Landry

docs/changelog.rst

@@ -2,8 +2,9 @@
 Changelog
 =========
 
-Changes in 0.6.X
-================
+Changes in 0.6.20
+=================
+- Added support for distinct and db_alias (MongoEngine/mongoengine#59)
 - Improved support for chained querysets when constraining the same fields (hmarr/mongoengine#554)
 - Fixed BinaryField lookup re (MongoEngine/mongoengine#48)
 

mongoengine/dereference.py

@@ -34,7 +34,9 @@ class DeReference(object):
 
         doc_type = None
         if instance and instance._fields:
-            doc_type = instance._fields[name].field
+            doc_type = instance._fields[name]
+            if hasattr(doc_type, 'field'):
+                doc_type = doc_type.field
 
             if isinstance(doc_type, ReferenceField):
                 doc_type = doc_type.document_type

mongoengine/queryset.py

@@ -1168,7 +1168,8 @@ class QuerySet(object):
         .. versionchanged:: 0.5 - Fixed handling references
         """
         from dereference import DeReference
-        return DeReference()(self._cursor.distinct(field), 1)
+        return DeReference()(self._cursor.distinct(field), 1,
+                             name=field, instance=self._document)
 
     def only(self, *fields):
         """Load only a subset of this document's fields. ::

tests/test_queryset.py

@@ -2299,6 +2299,28 @@ class QuerySetTest(unittest.TestCase):
 
         self.assertEquals(Foo.objects.distinct("bar"), [bar])
 
+    def test_distinct_handles_references_to_alias(self):
+        register_connection('testdb', 'mongoenginetest2')
+
+        class Foo(Document):
+            bar = ReferenceField("Bar")
+            meta = {'db_alias': 'testdb'}
+
+        class Bar(Document):
+            text = StringField()
+            meta = {'db_alias': 'testdb'}
+
+        Bar.drop_collection()
+        Foo.drop_collection()
+
+        bar = Bar(text="hi")
+        bar.save()
+
+        foo = Foo(bar=bar)
+        foo.save()
+
+        self.assertEquals(Foo.objects.distinct("bar"), [bar])
+
     def test_custom_manager(self):
         """Ensure that custom QuerySetManager instances work as expected.
         """