Resolve field name to db field name when using distinct(#260, #264, #269)

AUTHORS

@@ -129,3 +129,5 @@ that much better:
  * Jakub Kot
  * Jorge Bastida
  * Aleksandr Sorokoumov
+ * Yohan Graterol
+ * bool-dev

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.7.10
 =================
+- Resolve field name to db field name when using distinct(#260, #264, #269)
 - Added kwargs to doc.save to help interop with django (#223, #270)
 - Fixed cloning querysets in PY3
 - Int fields no longer unset in save when changed to 0 (#272)

mongoengine/queryset.py

@@ -1212,6 +1212,9 @@ class QuerySet(object):
         .. versionchanged:: 0.5 - Fixed handling references
         .. versionchanged:: 0.6 - Improved db_field refrence handling
         """
+        try:
+            field = self._fields_to_dbfields([field]).pop()
+        finally:
             return self._dereference(self._cursor.distinct(field), 1,
                                      name=field, instance=self._document)
 

tests/test_queryset.py

@@ -2486,6 +2486,25 @@ class QuerySetTest(unittest.TestCase):
 
         self.assertEqual(Foo.objects.distinct("bar"), [bar])
 
+    def test_distinct_handles_db_field(self):
+        """Ensure that distinct resolves field name to db_field as expected.
+        """
+        class Product(Document):
+            product_id = IntField(db_field='pid')
+
+        Product.drop_collection()
+
+        Product(product_id=1).save()
+        Product(product_id=2).save()
+        Product(product_id=1).save()
+
+        self.assertEqual(set(Product.objects.distinct('product_id')),
+                         set([1, 2]))
+        self.assertEqual(set(Product.objects.distinct('pid')),
+                         set([1, 2]))
+
+        Product.drop_collection()
+
     def test_custom_manager(self):
         """Ensure that custom QuerySetManager instances work as expected.
         """