Fix BaseQuerySet#sum and BaseQuerySet#average for fields that specify a db_field

* added flake8 and flake8-import-order to travis for py27

* fixed a test that fails from time to time depending on an order of a dict

* flake8 tweaks for the entire codebase excluding tests

README.rst

@@ -6,15 +6,15 @@ MongoEngine
 :Author: Harry Marr (http://github.com/hmarr)
 :Maintainer: Ross Lawley (http://github.com/rozza)
 
-.. image:: https://secure.travis-ci.org/MongoEngine/mongoengine.png?branch=master
-  :target: http://travis-ci.org/MongoEngine/mongoengine
+.. image:: https://travis-ci.org/MongoEngine/mongoengine.svg?branch=master
+  :target: https://travis-ci.org/MongoEngine/mongoengine
 
-.. image:: https://coveralls.io/repos/MongoEngine/mongoengine/badge.png?branch=master
-  :target: https://coveralls.io/r/MongoEngine/mongoengine?branch=master
+.. image:: https://coveralls.io/repos/github/MongoEngine/mongoengine/badge.svg?branch=master
+  :target: https://coveralls.io/github/MongoEngine/mongoengine?branch=master
 
-.. image:: https://landscape.io/github/MongoEngine/mongoengine/master/landscape.png
-   :target: https://landscape.io/github/MongoEngine/mongoengine/master
-   :alt: Code Health
+.. image:: https://landscape.io/github/MongoEngine/mongoengine/master/landscape.svg?style=flat
+  :target: https://landscape.io/github/MongoEngine/mongoengine/master
+  :alt: Code Health
 
 About
 =====

docs/changelog.rst

@@ -27,6 +27,7 @@ Changes in 0.10.7
 - Added support for pickling QuerySet instances. #1397
 - Fixed connecting to a list of hosts #1389
 - Fixed a bug where accessing broken references wouldn't raise a DoesNotExist error #1334
+- Fixed not being able to specify use_db_field=False on ListField(EmbeddedDocumentField) instances #1218
 - Improvements to the dictionary fields docs # 1383
 
 Changes in 0.10.6

mongoengine/queryset/base.py

@@ -1271,9 +1271,10 @@ class BaseQuerySet(object):
         :param field: the field to sum over; use dot notation to refer to
             embedded document fields
         """
+        db_field = self._fields_to_dbfields([field]).pop()
         pipeline = [
             {'$match': self._query},
-            {'$group': {'_id': 'sum', 'total': {'$sum': '$' + field}}}
+            {'$group': {'_id': 'sum', 'total': {'$sum': '$' + db_field}}}
         ]
 
         # if we're performing a sum over a list field, we sum up all the
@@ -1300,9 +1301,10 @@ class BaseQuerySet(object):
         :param field: the field to average over; use dot notation to refer to
             embedded document fields
         """
+        db_field = self._fields_to_dbfields([field]).pop()
         pipeline = [
             {'$match': self._query},
-            {'$group': {'_id': 'avg', 'total': {'$avg': '$' + field}}}
+            {'$group': {'_id': 'avg', 'total': {'$avg': '$' + db_field}}}
         ]
 
         # if we're performing an average over a list field, we average out

tests/queryset/queryset.py

@@ -2838,6 +2838,34 @@ class QuerySetTest(unittest.TestCase):
             sum([a for a in ages if a >= 50])
         )
 
+    def test_sum_over_db_field(self):
+        """Ensure that a field mapped to a db field with a different name
+        can be summed over correctly.
+        """
+        class UserVisit(Document):
+            num_visits = IntField(db_field='visits')
+
+        UserVisit.drop_collection()
+
+        UserVisit.objects.create(num_visits=10)
+        UserVisit.objects.create(num_visits=5)
+
+        self.assertEqual(UserVisit.objects.sum('num_visits'), 15)
+
+    def test_average_over_db_field(self):
+        """Ensure that a field mapped to a db field with a different name
+        can have its average computed correctly.
+        """
+        class UserVisit(Document):
+            num_visits = IntField(db_field='visits')
+
+        UserVisit.drop_collection()
+
+        UserVisit.objects.create(num_visits=20)
+        UserVisit.objects.create(num_visits=10)
+
+        self.assertEqual(UserVisit.objects.average('num_visits'), 15)
+
     def test_embedded_average(self):
         class Pay(EmbeddedDocument):
             value = DecimalField()