version bump (forgot to do it with v0.10.8 release, so have to go for v0.10.9)

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

.gitignore

@@ -14,4 +14,6 @@ env/
 .project
 .pydevproject
 tests/test_bugfix.py
-htmlcov/
+htmlcov/
+venv
+venv3

.travis.yml

@@ -1,41 +1,58 @@
 language: python
+
 python:
-- '2.6'
+- '2.6'  # TODO remove in v0.11.0
 - '2.7'
 - '3.3'
 - '3.4'
 - '3.5'
 - pypy
 - pypy3
+
 env:
 - PYMONGO=2.7
 - PYMONGO=2.8
 - PYMONGO=3.0
 - PYMONGO=dev
+
 matrix:
   fast_finish: true
+
 before_install:
 - travis_retry sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10
 - echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' |
   sudo tee /etc/apt/sources.list.d/mongodb.list
 - travis_retry sudo apt-get update
 - travis_retry sudo apt-get install mongodb-org-server
+
 install:
 - sudo apt-get install python-dev python3-dev libopenjpeg-dev zlib1g-dev libjpeg-turbo8-dev
   libtiff4-dev libjpeg8-dev libfreetype6-dev liblcms2-dev libwebp-dev tcl8.5-dev tk8.5-dev
   python-tk
-# virtualenv>=14.0.0 has dropped Python 3.2 support
-- travis_retry pip install "virtualenv<14.0.0" "tox>=1.9" coveralls
+- travis_retry pip install --upgrade pip
+- travis_retry pip install coveralls
+- travis_retry pip install flake8
+- travis_retry pip install tox>=1.9
+- travis_retry pip install "virtualenv<14.0.0"  # virtualenv>=14.0.0 has dropped Python 3.2 support (and pypy3 is based on py32)
 - travis_retry tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -e test
+
+# Run flake8 for py27
+before_script:
+- if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then tox -e flake8; fi
+
 script:
 - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- --with-coverage
+
 after_script: coveralls --verbose
+
 notifications:
   irc: irc.freenode.org#mongoengine
+
 branches:
   only:
   - master
   - /^v.*$/
+
 deploy:
   provider: pypi
   user: the_drow

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
 =====
@@ -52,10 +52,14 @@ Some simple examples of what MongoEngine code looks like:
 
 .. code :: python
 
+    from mongoengine import *
+    connect('mydb')
+
     class BlogPost(Document):
         title = StringField(required=True, max_length=200)
         posted = DateTimeField(default=datetime.datetime.now)
         tags = ListField(StringField(max_length=50))
+        meta = {'allow_inheritance': True}
 
     class TextPost(BlogPost):
         content = StringField(required=True)

docs/changelog.rst

@@ -4,14 +4,25 @@ Changelog
 
 Changes in 0.10.8
 =================
-- Fill this in as PRs for v0.10.8 are merged
+- Added support for QuerySet.batch_size (#1426)
+- Fixed query set iteration within iteration #1427
+- Fixed an issue where specifying a MongoDB URI host would override more information than it should #1421
+- Added ability to filter the generic reference field by ObjectId and DBRef #1425
+- Fixed delete cascade for models with a custom primary key field #1247
+- Added ability to specify an authentication mechanism (e.g. X.509) #1333
+- Added support for falsey primary keys (e.g. doc.pk = 0) #1354
+- Fixed QuerySet#sum/average for fields w/ explicit db_field #1417
+- Fixed filtering by embedded_doc=None #1422
+- Added support for cursor.comment #1420
+- Fixed doc.get_<field>_display #1419
+- Fixed __repr__ method of the StrictDict #1424
+- Added a deprecation warning for Python 2.6
 
 Changes in 0.10.7
 =================
 - Dropped Python 3.2 support #1390
 - Fixed the bug where dynamic doc has index inside a dict field #1278
 - Fixed: ListField minus index assignment does not work #1128
-- Fixed not being able to specify `use_db_field=False` on `ListField(EmbeddedDocumentField)` instances
 - Fixed cascade delete mixing among collections #1224
 - Add `signal_kwargs` argument to `Document.save`, `Document.delete` and `BaseQuerySet.insert` to be passed to signals calls #1206
 - Raise `OperationError` when trying to do a `drop_collection` on document with no collection set.
@@ -27,7 +38,8 @@ 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
-- Improvements to the dictionary fields docs # 1383
+- 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/__init__.py

@@ -1,20 +1,20 @@
-import document
-from document import *
-import fields
-from fields import *
 import connection
 from connection import *
+import document
+from document import *
+import errors
+from errors import *
+import fields
+from fields import *
 import queryset
 from queryset import *
 import signals
 from signals import *
-from errors import *
-import errors
 
 __all__ = (list(document.__all__) + fields.__all__ + connection.__all__ +
            list(queryset.__all__) + signals.__all__ + list(errors.__all__))
 
-VERSION = (0, 10, 7)
+VERSION = (0, 10, 9)
 
 
 def get_version():
@@ -22,4 +22,5 @@ def get_version():
         return '.'.join(map(str, VERSION[:-1])) + VERSION[-1]
     return '.'.join(map(str, VERSION))
 
+
 __version__ = get_version()

mongoengine/base/datastructures.py

@@ -1,5 +1,5 @@
-import weakref
 import itertools
+import weakref
 
 from mongoengine.common import _import_class
 from mongoengine.errors import DoesNotExist, MultipleObjectsReturned
@@ -199,8 +199,9 @@ class BaseList(list):
     def _mark_as_changed(self, key=None):
         if hasattr(self._instance, '_mark_as_changed'):
             if key:
-                self._instance._mark_as_changed('%s.%s' % (self._name, 
-                    key % len(self)))
+                self._instance._mark_as_changed(
+                    '%s.%s' % (self._name, key % len(self))
+                )
             else:
                 self._instance._mark_as_changed(self._name)
 
@@ -437,7 +438,7 @@ class StrictDict(object):
                 __slots__ = allowed_keys_tuple
 
                 def __repr__(self):
-                    return "{%s}" % ', '.join('"{0!s}": {0!r}'.format(k) for k in self.iterkeys())
+                    return "{%s}" % ', '.join('"{0!s}": {1!r}'.format(k, v) for k, v in self.items())
 
             cls._classes[allowed_keys] = SpecificStrictDict
         return cls._classes[allowed_keys]

mongoengine/base/document.py

@@ -1,28 +1,28 @@
 import copy
-import operator
 import numbers
+import operator
 from collections import Hashable
 from functools import partial
 
-import pymongo
-from bson import json_util, ObjectId
+from bson import ObjectId, json_util
 from bson.dbref import DBRef
 from bson.son import SON
+import pymongo
 
 from mongoengine import signals
-from mongoengine.common import _import_class
-from mongoengine.errors import (ValidationError, InvalidDocumentError,
-                                LookUpError, FieldDoesNotExist)
-from mongoengine.python_support import PY3, txt_type
-from mongoengine.base.common import get_document, ALLOW_INHERITANCE
+from mongoengine.base.common import ALLOW_INHERITANCE, get_document
 from mongoengine.base.datastructures import (
     BaseDict,
     BaseList,
     EmbeddedDocumentList,
-    StrictDict,
-    SemiStrictDict
+    SemiStrictDict,
+    StrictDict
 )
 from mongoengine.base.fields import ComplexBaseField
+from mongoengine.common import _import_class
+from mongoengine.errors import (FieldDoesNotExist, InvalidDocumentError,
+                                LookUpError, ValidationError)
+from mongoengine.python_support import PY3, txt_type
 
 __all__ = ('BaseDocument', 'NON_FIELD_ERRORS')
 
@@ -73,7 +73,7 @@ class BaseDocument(object):
         # if so raise an Exception.
         if not self._dynamic and (self._meta.get('strict', True) or _created):
             _undefined_fields = set(values.keys()) - set(
-              self._fields.keys() + ['id', 'pk', '_cls', '_text_score'])
+                self._fields.keys() + ['id', 'pk', '_cls', '_text_score'])
             if _undefined_fields:
                 msg = (
                     "The fields '{0}' do not exist on the document '{1}'"
@@ -121,7 +121,7 @@ class BaseDocument(object):
                 else:
                     self._data[key] = value
 
-        # Set any get_fieldname_display methods
+        # Set any get_<field>_display methods
         self.__set_field_display()
 
         if self._dynamic:
@@ -310,7 +310,7 @@ class BaseDocument(object):
         data = SON()
         data["_id"] = None
         data['_cls'] = self._class_name
-        
+
         # only root fields ['test1.a', 'test2'] => ['test1', 'test2']
         root_fields = set([f.split('.')[0] for f in fields])
 
@@ -333,11 +333,11 @@ class BaseDocument(object):
                         i.replace(key, '') for i in fields
                         if i.startswith(key)]
 
-                    ex_vars['fields'] = embedded_fields 
+                    ex_vars['fields'] = embedded_fields
 
                 if 'use_db_field' in f_inputs:
                     ex_vars['use_db_field'] = use_db_field
-                     
+
                 value = field.to_mongo(value, **ex_vars)
 
             # Handle self generating fields
@@ -566,8 +566,10 @@ class BaseDocument(object):
                     continue
             if isinstance(field, ReferenceField):
                 continue
-            elif (isinstance(data, (EmbeddedDocument, DynamicEmbeddedDocument))
-                  and db_field_name not in changed_fields):
+            elif (
+                isinstance(data, (EmbeddedDocument, DynamicEmbeddedDocument)) and
+                db_field_name not in changed_fields
+            ):
                 # Find all embedded fields that have been changed
                 changed = data._get_changed_fields(inspected)
                 changed_fields += ["%s%s" % (key, k) for k in changed if k]
@@ -608,7 +610,7 @@ class BaseDocument(object):
                         break
                     elif isinstance(d, list) and p.lstrip('-').isdigit():
                         if p[0] == '-':
-                            p = str(len(d)+int(p))
+                            p = str(len(d) + int(p))
                         try:
                             d = d[int(p)]
                         except IndexError:
@@ -644,7 +646,7 @@ class BaseDocument(object):
                 for p in parts:
                     if isinstance(d, list) and p.lstrip('-').isdigit():
                         if p[0] == '-':
-                            p = str(len(d)+int(p))
+                            p = str(len(d) + int(p))
                         d = d[int(p)]
                     elif (hasattr(d, '__getattribute__') and
                           not isinstance(d, dict)):
@@ -775,8 +777,12 @@ class BaseDocument(object):
         # Check to see if we need to include _cls
         allow_inheritance = cls._meta.get('allow_inheritance',
                                           ALLOW_INHERITANCE)
-        include_cls = (allow_inheritance and not spec.get('sparse', False) and
-                       spec.get('cls',  True) and '_cls' not in spec['fields'])
+        include_cls = (
+            allow_inheritance and
+            not spec.get('sparse', False) and
+            spec.get('cls', True) and
+            '_cls' not in spec['fields']
+        )
 
         # 733: don't include cls if index_cls is False unless there is an explicit cls with the index
         include_cls = include_cls and (spec.get('cls', False) or cls._meta.get('index_cls', True))
@@ -999,19 +1005,18 @@ class BaseDocument(object):
         return '.'.join(parts)
 
     def __set_field_display(self):
-        """Dynamically set the display value for a field with choices"""
-        for attr_name, field in self._fields.items():
-            if field.choices:
-                if self._dynamic:
-                    obj = self
-                else:
-                    obj = type(self)
-                setattr(obj,
-                        'get_%s_display' % attr_name,
-                        partial(self.__get_field_display, field=field))
+        """For each field that specifies choices, create a
+        get_<field>_display method.
+        """
+        fields_with_choices = [(n, f) for n, f in self._fields.items()
+                               if f.choices]
+        for attr_name, field in fields_with_choices:
+            setattr(self,
+                    'get_%s_display' % attr_name,
+                    partial(self.__get_field_display, field=field))
 
     def __get_field_display(self, field):
-        """Returns the display value for a choice field"""
+        """Return the display value for a choice field"""
         value = getattr(self, field.name)
         if field.choices and isinstance(field.choices[0], (list, tuple)):
             return dict(field.choices).get(value, value)

mongoengine/base/fields.py

@@ -5,12 +5,12 @@ import weakref
 from bson import DBRef, ObjectId, SON
 import pymongo
 
-from mongoengine.common import _import_class
-from mongoengine.errors import ValidationError
 from mongoengine.base.common import ALLOW_INHERITANCE
 from mongoengine.base.datastructures import (
     BaseDict, BaseList, EmbeddedDocumentList
 )
+from mongoengine.common import _import_class
+from mongoengine.errors import ValidationError
 
 __all__ = ("BaseField", "ComplexBaseField",
            "ObjectIdField", "GeoJsonBaseField")
@@ -85,13 +85,13 @@ class BaseField(object):
         self.null = null
         self.sparse = sparse
         self._owner_document = None
-        
+
         # Detect and report conflicts between metadata and base properties.
         conflicts = set(dir(self)) & set(kwargs)
         if conflicts:
             raise TypeError("%s already has attribute(s): %s" % (
-                self.__class__.__name__, ', '.join(conflicts) ))
-        
+                self.__class__.__name__, ', '.join(conflicts)))
+
         # Assign metadata to the instance
         # This efficient method is available because no __slots__ are defined.
         self.__dict__.update(kwargs)
@@ -169,11 +169,11 @@ class BaseField(object):
         f_inputs = self.to_mongo.__code__.co_varnames
         ex_vars = {}
         if 'fields' in f_inputs:
-            ex_vars['fields'] = fields 
+            ex_vars['fields'] = fields
 
         if 'use_db_field' in f_inputs:
             ex_vars['use_db_field'] = use_db_field
-             
+
         return self.to_mongo(value, **ex_vars)
 
     def prepare_query_value(self, op, value):
@@ -206,7 +206,6 @@ class BaseField(object):
         elif value not in choice_list:
             self.error('Value must be one of %s' % unicode(choice_list))
 
-
     def _validate(self, value, **kwargs):
         # Check the Choices Constraint
         if self.choices:

mongoengine/base/metaclasses.py

@@ -1,5 +1,7 @@
 import warnings
 
+from mongoengine.base.common import ALLOW_INHERITANCE, _document_registry
+from mongoengine.base.fields import BaseField, ComplexBaseField, ObjectIdField
 from mongoengine.common import _import_class
 from mongoengine.errors import InvalidDocumentError
 from mongoengine.python_support import PY3
@@ -7,16 +9,14 @@ from mongoengine.queryset import (DO_NOTHING, DoesNotExist,
                                   MultipleObjectsReturned,
                                   QuerySetManager)
 
-from mongoengine.base.common import _document_registry, ALLOW_INHERITANCE
-from mongoengine.base.fields import BaseField, ComplexBaseField, ObjectIdField
 
 __all__ = ('DocumentMetaclass', 'TopLevelDocumentMetaclass')
 
 
 class DocumentMetaclass(type):
-    """Metaclass for all documents.
-    """
+    """Metaclass for all documents."""
 
+    # TODO lower complexity of this method
     def __new__(cls, name, bases, attrs):
         flattened_bases = cls._get_bases(bases)
         super_new = super(DocumentMetaclass, cls).__new__
@@ -162,7 +162,7 @@ class DocumentMetaclass(type):
         # copies __func__ into im_func and __self__ into im_self for
         # classmethod objects in Document derived classes.
         if PY3:
-            for key, val in new_class.__dict__.items():
+            for val in new_class.__dict__.values():
                 if isinstance(val, classmethod):
                     f = val.__get__(new_class)
                     if hasattr(f, '__func__') and not hasattr(f, 'im_func'):

mongoengine/connection.py

@@ -6,6 +6,7 @@ __all__ = ['ConnectionError', 'connect', 'register_connection',
 
 
 DEFAULT_CONNECTION_NAME = 'default'
+
 if IS_PYMONGO_3:
     READ_PREFERENCE = ReadPreference.PRIMARY
 else:
@@ -24,7 +25,9 @@ _dbs = {}
 
 def register_connection(alias, name=None, host=None, port=None,
                         read_preference=READ_PREFERENCE,
-                        username=None, password=None, authentication_source=None,
+                        username=None, password=None,
+                        authentication_source=None,
+                        authentication_mechanism=None,
                         **kwargs):
     """Add a connection.
 
@@ -38,6 +41,9 @@ def register_connection(alias, name=None, host=None, port=None,
     :param username: username to authenticate with
     :param password: password to authenticate with
     :param authentication_source: database to authenticate against
+    :param authentication_mechanism: database authentication mechanisms.
+        By default, use SCRAM-SHA-1 with MongoDB 3.0 and later,
+        MONGODB-CR (MongoDB Challenge Response protocol) for older servers.
     :param is_mock: explicitly use mongomock for this connection
         (can also be done by using `mongomock://` as db host prefix)
     :param kwargs: allow ad-hoc parameters to be passed into the pymongo driver
@@ -53,9 +59,11 @@ def register_connection(alias, name=None, host=None, port=None,
         'read_preference': read_preference,
         'username': username,
         'password': password,
-        'authentication_source': authentication_source
+        'authentication_source': authentication_source,
+        'authentication_mechanism': authentication_mechanism
     }
 
+    # Handle uri style connections
     conn_host = conn_settings['host']
     # host can be a list or a string, so if string, force to a list
     if isinstance(conn_host, str_types):
@@ -63,25 +71,33 @@ def register_connection(alias, name=None, host=None, port=None,
 
     resolved_hosts = []
     for entity in conn_host:
-        # Handle uri style connections
+
+        # Handle Mongomock
         if entity.startswith('mongomock://'):
             conn_settings['is_mock'] = True
             # `mongomock://` is not a valid url prefix and must be replaced by `mongodb://`
             resolved_hosts.append(entity.replace('mongomock://', 'mongodb://', 1))
+
+        # Handle URI style connections, only updating connection params which
+        # were explicitly specified in the URI.
         elif '://' in entity:
             uri_dict = uri_parser.parse_uri(entity)
             resolved_hosts.append(entity)
-            conn_settings.update({
-                'name': uri_dict.get('database') or name,
-                'username': uri_dict.get('username'),
-                'password': uri_dict.get('password'),
-                'read_preference': read_preference,
-            })
+
+            if uri_dict.get('database'):
+                conn_settings['name'] = uri_dict.get('database')
+
+            for param in ('read_preference', 'username', 'password'):
+                if uri_dict.get(param):
+                    conn_settings[param] = uri_dict[param]
+
             uri_options = uri_dict['options']
             if 'replicaset' in uri_options:
                 conn_settings['replicaSet'] = True
             if 'authsource' in uri_options:
                 conn_settings['authentication_source'] = uri_options['authsource']
+            if 'authmechanism' in uri_options:
+                conn_settings['authentication_mechanism'] = uri_options['authmechanism']
         else:
             resolved_hosts.append(entity)
     conn_settings['host'] = resolved_hosts
@@ -123,6 +139,7 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
         conn_settings.pop('username', None)
         conn_settings.pop('password', None)
         conn_settings.pop('authentication_source', None)
+        conn_settings.pop('authentication_mechanism', None)
 
         is_mock = conn_settings.pop('is_mock', None)
         if is_mock:
@@ -157,6 +174,7 @@ def get_connection(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
                 connection_settings.pop('username', None)
                 connection_settings.pop('password', None)
                 connection_settings.pop('authentication_source', None)
+                connection_settings.pop('authentication_mechanism', None)
                 if conn_settings == connection_settings and _connections.get(db_alias, None):
                     connection = _connections[db_alias]
                     break
@@ -176,11 +194,13 @@ def get_db(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
         conn = get_connection(alias)
         conn_settings = _connection_settings[alias]
         db = conn[conn_settings['name']]
+        auth_kwargs = {'source': conn_settings['authentication_source']}
+        if conn_settings['authentication_mechanism'] is not None:
+            auth_kwargs['mechanism'] = conn_settings['authentication_mechanism']
         # Authenticate if necessary
-        if conn_settings['username'] and conn_settings['password']:
-            db.authenticate(conn_settings['username'],
-                            conn_settings['password'],
-                            source=conn_settings['authentication_source'])
+        if conn_settings['username'] and (conn_settings['password'] or
+                                          conn_settings['authentication_mechanism'] == 'MONGODB-X509'):
+            db.authenticate(conn_settings['username'], conn_settings['password'], **auth_kwargs)
         _dbs[alias] = db
     return _dbs[alias]
 

mongoengine/dereference.py

@@ -1,15 +1,14 @@
 from bson import DBRef, SON
 
-from mongoengine.python_support import txt_type
-
-from base import (
+from .base import (
     BaseDict, BaseList, EmbeddedDocumentList,
     TopLevelDocumentMetaclass, get_document
 )
-from fields import (ReferenceField, ListField, DictField, MapField)
-from connection import get_db
-from queryset import QuerySet
-from document import Document, EmbeddedDocument
+from .connection import get_db
+from .document import Document, EmbeddedDocument
+from .fields import DictField, ListField, MapField, ReferenceField
+from .python_support import txt_type
+from .queryset import QuerySet
 
 
 class DeReference(object):

mongoengine/document.py

@@ -1,28 +1,29 @@
-import warnings
-import pymongo
 import re
+import warnings
 
-from pymongo.read_preferences import ReadPreference
 from bson.dbref import DBRef
+import pymongo
+from pymongo.read_preferences import ReadPreference
+
 from mongoengine import signals
-from mongoengine.common import _import_class
 from mongoengine.base import (
-    DocumentMetaclass,
-    TopLevelDocumentMetaclass,
-    BaseDocument,
-    BaseDict,
-    BaseList,
-    EmbeddedDocumentList,
     ALLOW_INHERITANCE,
+    BaseDict,
+    BaseDocument,
+    BaseList,
+    DocumentMetaclass,
+    EmbeddedDocumentList,
+    TopLevelDocumentMetaclass,
     get_document
 )
-from mongoengine.errors import (InvalidQueryError, InvalidDocumentError,
+from mongoengine.common import _import_class
+from mongoengine.connection import DEFAULT_CONNECTION_NAME, get_db
+from mongoengine.context_managers import switch_collection, switch_db
+from mongoengine.errors import (InvalidDocumentError, InvalidQueryError,
                                 SaveConditionError)
 from mongoengine.python_support import IS_PYMONGO_3
-from mongoengine.queryset import (OperationError, NotUniqueError,
+from mongoengine.queryset import (NotUniqueError, OperationError,
                                   QuerySet, transform)
-from mongoengine.connection import get_db, DEFAULT_CONNECTION_NAME
-from mongoengine.context_managers import switch_db, switch_collection
 
 __all__ = ('Document', 'EmbeddedDocument', 'DynamicDocument',
            'DynamicEmbeddedDocument', 'OperationError',
@@ -332,8 +333,10 @@ class Document(BaseDocument):
                     # Correct behaviour in 2.X and in 3.0.1+ versions
                     if not object_id and pymongo.version_tuple == (3, 0):
                         pk_as_mongo_obj = self._fields.get(self._meta['id_field']).to_mongo(self.pk)
-                        object_id = self._qs.filter(pk=pk_as_mongo_obj).first() and \
-                                    self._qs.filter(pk=pk_as_mongo_obj).first().pk
+                        object_id = (
+                            self._qs.filter(pk=pk_as_mongo_obj).first() and
+                            self._qs.filter(pk=pk_as_mongo_obj).first().pk
+                        )  # TODO doesn't this make 2 queries?
             else:
                 object_id = doc['_id']
                 updates, removals = self._delta()
@@ -469,7 +472,7 @@ class Document(BaseDocument):
         Raises :class:`OperationError` if called on an object that has not yet
         been saved.
         """
-        if not self.pk:
+        if self.pk is None:
             if kwargs.get('upsert', False):
                 query = self.to_mongo()
                 if "_cls" in query:
@@ -501,10 +504,10 @@ class Document(BaseDocument):
         signal_kwargs = signal_kwargs or {}
         signals.pre_delete.send(self.__class__, document=self, **signal_kwargs)
 
-        # Delete FileFields separately 
+        # Delete FileFields separately
         FileField = _import_class('FileField')
         for name, field in self._fields.iteritems():
-            if isinstance(field, FileField): 
+            if isinstance(field, FileField):
                 getattr(self, name).delete()
 
         try:
@@ -601,7 +604,7 @@ class Document(BaseDocument):
         elif "max_depth" in kwargs:
             max_depth = kwargs["max_depth"]
 
-        if not self.pk:
+        if self.pk is None:
             raise self.DoesNotExist("Document does not exist")
         obj = self._qs.read_preference(ReadPreference.PRIMARY).filter(
             **self._object_key).only(*fields).limit(
@@ -652,7 +655,7 @@ class Document(BaseDocument):
     def to_dbref(self):
         """Returns an instance of :class:`~bson.dbref.DBRef` useful in
         `__raw__` queries."""
-        if not self.pk:
+        if self.pk is None:
             msg = "Only saved documents can have a valid dbref"
             raise OperationError(msg)
         return DBRef(self.__class__._get_collection_name(), self.pk)

mongoengine/fields.py

@@ -8,6 +8,9 @@ import uuid
 import warnings
 from operator import itemgetter
 
+from bson import Binary, DBRef, ObjectId, SON
+import gridfs
+import pymongo
 import six
 
 try:
@@ -17,22 +20,18 @@ except ImportError:
 else:
     import dateutil.parser
 
-import pymongo
-import gridfs
-from bson import Binary, DBRef, SON, ObjectId
 try:
     from bson.int64 import Int64
 except ImportError:
     Int64 = long
 
-from mongoengine.errors import ValidationError, DoesNotExist
-from mongoengine.python_support import (PY3, bin_type, txt_type,
-                                        str_types, StringIO)
-from base import (BaseField, ComplexBaseField, ObjectIdField, GeoJsonBaseField,
-                  get_document, BaseDocument)
-from queryset import DO_NOTHING, QuerySet
-from document import Document, EmbeddedDocument
-from connection import get_db, DEFAULT_CONNECTION_NAME
+from .base import (BaseDocument, BaseField, ComplexBaseField, GeoJsonBaseField,
+                   ObjectIdField, get_document)
+from .connection import DEFAULT_CONNECTION_NAME, get_db
+from .document import Document, EmbeddedDocument
+from .errors import DoesNotExist, ValidationError
+from .python_support import PY3, StringIO, bin_type, str_types, txt_type
+from .queryset import DO_NOTHING, QuerySet
 
 try:
     from PIL import Image, ImageOps
@@ -578,7 +577,7 @@ class EmbeddedDocumentField(BaseField):
         return self.document_type._fields.get(member_name)
 
     def prepare_query_value(self, op, value):
-        if not isinstance(value, self.document_type):
+        if value is not None and not isinstance(value, self.document_type):
             value = self.document_type._from_son(value)
         super(EmbeddedDocumentField, self).prepare_query_value(op, value)
         return self.to_mongo(value)
@@ -1015,11 +1014,10 @@ class ReferenceField(BaseField):
 
         if self.document_type._meta.get('abstract') and \
                 not isinstance(value, self.document_type):
-            self.error('%s is not an instance of abstract reference'
-                    ' type %s' % (value._class_name,
-                        self.document_type._class_name)
-                    )
-
+            self.error(
+                '%s is not an instance of abstract reference type %s' % (
+                    self.document_type._class_name)
+            )
 
     def lookup_member(self, member_name):
         return self.document_type._fields.get(member_name)
@@ -1126,7 +1124,7 @@ class CachedReferenceField(BaseField):
             new_fields = [f for f in self.fields if f in fields]
         else:
             new_fields = self.fields
-            
+
         value.update(dict(document.to_mongo(use_db_field, fields=new_fields)))
         return value
 
@@ -1251,7 +1249,7 @@ class GenericReferenceField(BaseField):
         if document is None:
             return None
 
-        if isinstance(document, (dict, SON)):
+        if isinstance(document, (dict, SON, ObjectId, DBRef)):
             return document
 
         id_field_name = document.__class__._meta['id_field']

mongoengine/python_support.py

@@ -1,9 +1,22 @@
-"""Helper functions and types to aid with Python 2.5 - 3 support."""
+"""Helper functions and types to aid with Python 2.6 - 3 support."""
 
 import sys
+import warnings
+
 import pymongo
 
 
+# Show a deprecation warning for people using Python v2.6
+# TODO remove in mongoengine v0.11.0
+if sys.version_info[0] == 2 and sys.version_info[1] == 6:
+    warnings.warn(
+        'Python v2.6 support is deprecated and is going to be dropped '
+        'entirely in the upcoming v0.11.0 release. Update your Python '
+        'version if you want to have access to the latest features and '
+        'bug fixes in MongoEngine.',
+        DeprecationWarning
+    )
+
 if pymongo.version_tuple[0] < 3:
     IS_PYMONGO_3 = False
 else:

mongoengine/queryset/__init__.py

@@ -1,6 +1,6 @@
-from mongoengine.errors import (DoesNotExist, MultipleObjectsReturned,
-                                InvalidQueryError, OperationError,
-                                NotUniqueError)
+from mongoengine.errors import (DoesNotExist, InvalidQueryError,
+                                MultipleObjectsReturned, NotUniqueError,
+                                OperationError)
 from mongoengine.queryset.field_list import *
 from mongoengine.queryset.manager import *
 from mongoengine.queryset.queryset import *

mongoengine/queryset/base.py

@@ -7,20 +7,19 @@ import pprint
 import re
 import warnings
 
-from bson import SON
+from bson import SON, json_util
 from bson.code import Code
-from bson import json_util
 import pymongo
 import pymongo.errors
 from pymongo.common import validate_read_preference
 
 from mongoengine import signals
+from mongoengine.base.common import get_document
+from mongoengine.common import _import_class
 from mongoengine.connection import get_db
 from mongoengine.context_managers import switch_db
-from mongoengine.common import _import_class
-from mongoengine.base.common import get_document
-from mongoengine.errors import (OperationError, NotUniqueError,
-                                InvalidQueryError, LookUpError)
+from mongoengine.errors import (InvalidQueryError, LookUpError,
+                                NotUniqueError, OperationError)
 from mongoengine.python_support import IS_PYMONGO_3
 from mongoengine.queryset import transform
 from mongoengine.queryset.field_list import QueryFieldList
@@ -83,6 +82,7 @@ class BaseQuerySet(object):
         self._limit = None
         self._skip = None
         self._hint = -1  # Using -1 as None is a valid value for hint
+        self._batch_size = None
         self.only_fields = []
         self._max_time_ms = None
 
@@ -155,10 +155,8 @@ class BaseQuerySet(object):
         # forse load cursor
         # self._cursor
 
-
     def __getitem__(self, key):
-        """Support skip and limit using getitem and slicing syntax.
-        """
+        """Support skip and limit using getitem and slicing syntax."""
         queryset = self.clone()
 
         # Slice provided
@@ -278,6 +276,8 @@ class BaseQuerySet(object):
         except StopIteration:
             return result
 
+        # If we were able to retrieve the 2nd doc, rewind the cursor and
+        # raise the MultipleObjectsReturned exception.
         queryset.rewind()
         message = u'%d items returned, instead of 1' % queryset.count()
         raise queryset._document.MultipleObjectsReturned(message)
@@ -447,7 +447,7 @@ class BaseQuerySet(object):
                 if doc._collection == document_cls._collection:
                     for ref in queryset:
                         cascade_refs.add(ref.id)
-                ref_q = document_cls.objects(**{field_name + '__in': self, 'id__nin': cascade_refs})
+                ref_q = document_cls.objects(**{field_name + '__in': self, 'pk__nin': cascade_refs})
                 ref_q_count = ref_q.count()
                 if ref_q_count > 0:
                     ref_q.delete(write_concern=write_concern, cascade_refs=cascade_refs)
@@ -529,8 +529,9 @@ class BaseQuerySet(object):
         .. versionadded:: 0.10.2
         """
 
-        atomic_update = self.update(multi=False, upsert=True, write_concern=write_concern,
-                             full_result=True, **update)
+        atomic_update = self.update(multi=False, upsert=True,
+                                    write_concern=write_concern,
+                                    full_result=True, **update)
 
         if atomic_update['updatedExisting']:
             document = self.get()
@@ -783,6 +784,19 @@ class BaseQuerySet(object):
         queryset._hint = index
         return queryset
 
+    def batch_size(self, size):
+        """Limit the number of documents returned in a single batch (each
+        batch requires a round trip to the server).
+
+        See http://api.mongodb.com/python/current/api/pymongo/cursor.html#pymongo.cursor.Cursor.batch_size
+        for details.
+
+        :param size: desired size of each batch.
+        """
+        queryset = self.clone()
+        queryset._batch_size = size
+        return queryset
+
     def distinct(self, field):
         """Return a list of distinct values for a given field.
 
@@ -935,6 +949,14 @@ class BaseQuerySet(object):
         queryset._ordering = queryset._get_order_by(keys)
         return queryset
 
+    def comment(self, text):
+        """Add a comment to the query.
+
+        See https://docs.mongodb.com/manual/reference/method/cursor.comment/#cursor.comment
+        for details.
+        """
+        return self._chainable_method("comment", text)
+
     def explain(self, format=False):
         """Return an explain plan record for the
         :class:`~mongoengine.queryset.QuerySet`\ 's cursor.
@@ -1273,9 +1295,10 @@ 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
@@ -1302,9 +1325,10 @@ 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
@@ -1459,6 +1483,9 @@ class BaseQuerySet(object):
             if self._hint != -1:
                 self._cursor_obj.hint(self._hint)
 
+            if self._batch_size is not None:
+                self._cursor_obj.batch_size(self._batch_size)
+
         return self._cursor_obj
 
     def __deepcopy__(self, memo):

mongoengine/queryset/queryset.py

@@ -1,6 +1,6 @@
 from mongoengine.errors import OperationError
-from mongoengine.queryset.base import (BaseQuerySet, DO_NOTHING, NULLIFY,
-                                       CASCADE, DENY, PULL)
+from mongoengine.queryset.base import (BaseQuerySet, CASCADE, DENY, DO_NOTHING,
+                                       NULLIFY, PULL)
 
 __all__ = ('QuerySet', 'QuerySetNoCache', 'DO_NOTHING', 'NULLIFY', 'CASCADE',
            'DENY', 'PULL')
@@ -27,9 +27,10 @@ class QuerySet(BaseQuerySet):
         in batches of ``ITER_CHUNK_SIZE``.
 
         If ``self._has_more`` the cursor hasn't been exhausted so cache then
-        batch.  Otherwise iterate the result_cache.
+        batch. Otherwise iterate the result_cache.
         """
         self._iter = True
+
         if self._has_more:
             return self._iter_results()
 
@@ -42,10 +43,12 @@ class QuerySet(BaseQuerySet):
         """
         if self._len is not None:
             return self._len
+
+        # Populate the result cache with *all* of the docs in the cursor
         if self._has_more:
-            # populate the cache
             list(self._iter_results())
 
+        # Cache the length of the complete result cache and return it
         self._len = len(self._result_cache)
         return self._len
 
@@ -64,18 +67,33 @@ class QuerySet(BaseQuerySet):
     def _iter_results(self):
         """A generator for iterating over the result cache.
 
-        Also populates the cache if there are more possible results to yield.
-        Raises StopIteration when there are no more results"""
+        Also populates the cache if there are more possible results to
+        yield. Raises StopIteration when there are no more results.
+        """
         if self._result_cache is None:
             self._result_cache = []
+
         pos = 0
         while True:
-            upper = len(self._result_cache)
-            while pos < upper:
+
+            # For all positions lower than the length of the current result
+            # cache, serve the docs straight from the cache w/o hitting the
+            # database.
+            # XXX it's VERY important to compute the len within the `while`
+            # condition because the result cache might expand mid-iteration
+            # (e.g. if we call len(qs) inside a loop that iterates over the
+            # queryset). Fortunately len(list) is O(1) in Python, so this
+            # doesn't cause performance issues.
+            while pos < len(self._result_cache):
                 yield self._result_cache[pos]
                 pos += 1
+
+            # Raise StopIteration if we already established there were no more
+            # docs in the db cursor.
             if not self._has_more:
                 raise StopIteration
+
+            # Otherwise, populate more of the cache and repeat.
             if len(self._result_cache) <= pos:
                 self._populate_cache()
 
@@ -86,12 +104,22 @@ class QuerySet(BaseQuerySet):
         """
         if self._result_cache is None:
             self._result_cache = []
-        if self._has_more:
-            try:
-                for i in xrange(ITER_CHUNK_SIZE):
-                    self._result_cache.append(self.next())
-            except StopIteration:
-                self._has_more = False
+
+        # Skip populating the cache if we already established there are no
+        # more docs to pull from the database.
+        if not self._has_more:
+            return
+
+        # Pull in ITER_CHUNK_SIZE docs from the database and store them in
+        # the result cache.
+        try:
+            for i in xrange(ITER_CHUNK_SIZE):
+                self._result_cache.append(self.next())
+        except StopIteration:
+            # Getting this exception means there are no more docs in the
+            # db cursor. Set _has_more to False so that we can use that
+            # information in other places.
+            self._has_more = False
 
     def count(self, with_limit_and_skip=False):
         """Count the selected elements in the query.

mongoengine/queryset/transform.py

@@ -1,11 +1,12 @@
 from collections import defaultdict
 
+from bson import ObjectId, SON
+from bson.dbref import DBRef
 import pymongo
-from bson import SON
 
 from mongoengine.base.fields import UPDATE_OPERATORS
-from mongoengine.connection import get_connection
 from mongoengine.common import _import_class
+from mongoengine.connection import get_connection
 from mongoengine.errors import InvalidQueryError
 from mongoengine.python_support import IS_PYMONGO_3
 
@@ -26,6 +27,7 @@ MATCH_OPERATORS = (COMPARISON_OPERATORS + GEO_OPERATORS +
                    STRING_OPERATORS + CUSTOM_OPERATORS)
 
 
+# TODO make this less complex
 def query(_doc_cls=None, **kwargs):
     """Transform a query from Django-style format to Mongo format.
     """
@@ -62,6 +64,7 @@ def query(_doc_cls=None, **kwargs):
             parts = []
 
             CachedReferenceField = _import_class('CachedReferenceField')
+            GenericReferenceField = _import_class('GenericReferenceField')
 
             cleaned_fields = []
             for field in fields:
@@ -101,6 +104,16 @@ def query(_doc_cls=None, **kwargs):
                 # 'in', 'nin' and 'all' require a list of values
                 value = [field.prepare_query_value(op, v) for v in value]
 
+            # If we're querying a GenericReferenceField, we need to alter the
+            # key depending on the value:
+            # * If the value is a DBRef, the key should be "field_name._ref".
+            # * If the value is an ObjectId, the key should be "field_name._ref.$id".
+            if isinstance(field, GenericReferenceField):
+                if isinstance(value, DBRef):
+                    parts[-1] += '._ref'
+                elif isinstance(value, ObjectId):
+                    parts[-1] += '._ref.$id'
+
         # if op and op not in COMPARISON_OPERATORS:
         if op:
             if op in GEO_OPERATORS:
@@ -108,8 +121,11 @@ def query(_doc_cls=None, **kwargs):
             elif op in ('match', 'elemMatch'):
                 ListField = _import_class('ListField')
                 EmbeddedDocumentField = _import_class('EmbeddedDocumentField')
-                if (isinstance(value, dict) and isinstance(field, ListField) and
-                    isinstance(field.field, EmbeddedDocumentField)):
+                if (
+                    isinstance(value, dict) and
+                    isinstance(field, ListField) and
+                    isinstance(field.field, EmbeddedDocumentField)
+                ):
                     value = query(field.field.document_type, **value)
                 else:
                     value = field.prepare_query_value(op, value)
@@ -125,11 +141,13 @@ def query(_doc_cls=None, **kwargs):
 
         for i, part in indices:
             parts.insert(i, part)
+
         key = '.'.join(parts)
+
         if op is None or key not in mongo_query:
             mongo_query[key] = value
         elif key in mongo_query:
-            if key in mongo_query and isinstance(mongo_query[key], dict):
+            if isinstance(mongo_query[key], dict):
                 mongo_query[key].update(value)
                 # $max/minDistance needs to come last - convert to SON
                 value_dict = mongo_query[key]

mongoengine/signals.py

@@ -29,7 +29,7 @@ except ImportError:
                                'because the blinker library is '
                                'not installed.')
 
-        send = lambda *a, **kw: None
+        send = lambda *a, **kw: None  # noqa
         connect = disconnect = has_receivers_for = receivers_for = \
             temporarily_connected_to = _fail
         del _fail

requirements.txt

@@ -1,3 +1,5 @@
 nose
 pymongo>=2.7.1
 six==1.10.0
+flake8
+flake8-import-order

setup.cfg

@@ -5,3 +5,9 @@ cover-erase = 1
 cover-branches = 1
 cover-package = mongoengine
 tests = tests
+
+[flake8]
+ignore=E501,F401,F403,F405,I201
+exclude=build,dist,docs,venv,.tox,.eggs,tests
+max-complexity=45
+application-import-names=mongoengine,tests

setup.py

@@ -1,6 +1,6 @@
 import os
 import sys
-from setuptools import setup, find_packages
+from setuptools import find_packages, setup
 
 # Hack to silence atexit traceback in newer python versions
 try:
@@ -8,8 +8,10 @@ try:
 except ImportError:
     pass
 
-DESCRIPTION = 'MongoEngine is a Python Object-Document ' + \
-'Mapper for working with MongoDB.'
+DESCRIPTION = (
+    'MongoEngine is a Python Object-Document '
+    'Mapper for working with MongoDB.'
+)
 
 try:
     with open('README.rst') as fin:
@@ -23,6 +25,7 @@ def get_version(version_tuple):
         return '.'.join(map(str, version_tuple[:-1])) + version_tuple[-1]
     return '.'.join(map(str, version_tuple))
 
+
 # Dirty hack to get version number from monogengine/__init__.py - we can't
 # import it as it depends on PyMongo and PyMongo isn't installed until this
 # file is read
@@ -64,21 +67,22 @@ else:
     if sys.version_info[0] == 2 and sys.version_info[1] == 6:
         extra_opts['tests_require'].append('unittest2')
 
-setup(name='mongoengine',
-      version=VERSION,
-      author='Harry Marr',
-      author_email='harry.marr@{nospam}gmail.com',
-      maintainer="Ross Lawley",
-      maintainer_email="ross.lawley@{nospam}gmail.com",
-      url='http://mongoengine.org/',
-      download_url='https://github.com/MongoEngine/mongoengine/tarball/master',
-      license='MIT',
-      include_package_data=True,
-      description=DESCRIPTION,
-      long_description=LONG_DESCRIPTION,
-      platforms=['any'],
-      classifiers=CLASSIFIERS,
-      install_requires=['pymongo>=2.7.1', 'six'],
-      test_suite='nose.collector',
-      **extra_opts
+setup(
+    name='mongoengine',
+    version=VERSION,
+    author='Harry Marr',
+    author_email='harry.marr@{nospam}gmail.com',
+    maintainer="Ross Lawley",
+    maintainer_email="ross.lawley@{nospam}gmail.com",
+    url='http://mongoengine.org/',
+    download_url='https://github.com/MongoEngine/mongoengine/tarball/master',
+    license='MIT',
+    include_package_data=True,
+    description=DESCRIPTION,
+    long_description=LONG_DESCRIPTION,
+    platforms=['any'],
+    classifiers=CLASSIFIERS,
+    install_requires=['pymongo>=2.7.1', 'six'],
+    test_suite='nose.collector',
+    **extra_opts
 )

tests/document/indexes.py

@@ -2,10 +2,8 @@
 import unittest
 import sys
 
-sys.path[0:0] = [""]
 
 import pymongo
-from random import randint
 
 from nose.plugins.skip import SkipTest
 from datetime import datetime
@@ -17,11 +15,9 @@ __all__ = ("IndexesTest", )
 
 
 class IndexesTest(unittest.TestCase):
-    _MAX_RAND = 10 ** 10
 
     def setUp(self):
-        self.db_name = 'mongoenginetest_IndexesTest_' + str(randint(0, self._MAX_RAND))
-        self.connection = connect(db=self.db_name)
+        self.connection = connect(db='mongoenginetest')
         self.db = get_db()
 
         class Person(Document):
@@ -844,7 +840,12 @@ class IndexesTest(unittest.TestCase):
 
         self.assertEqual({'text': 'OK', '_id': {'term': 'ok', 'name': 'n'}},
                          report.to_mongo())
-        self.assertEqual(report, ReportDictField.objects.get(pk=my_key))
+
+        # We can't directly call ReportDictField.objects.get(pk=my_key),
+        # because dicts are unordered, and if the order in MongoDB is
+        # different than the one in `my_key`, this test will fail.
+        self.assertEqual(report, ReportDictField.objects.get(pk__name=my_key['name']))
+        self.assertEqual(report, ReportDictField.objects.get(pk__term=my_key['term']))
 
     def test_string_indexes(self):
 

tests/document/instance.py

@@ -3202,5 +3202,20 @@ class InstanceTest(unittest.TestCase):
             self.assertEqual(b._instance, a)
         self.assertEqual(idx, 2)
 
+    def test_falsey_pk(self):
+        """Ensure that we can create and update a document with Falsey PK.
+        """
+        class Person(Document):
+            age = IntField(primary_key=True)
+            height = FloatField()
+
+        person = Person()
+        person.age = 0
+        person.height = 1.89
+        person.save()
+
+        person.update(set__height=2.0)
+
+
 if __name__ == '__main__':
     unittest.main()

tests/fields/fields.py

@@ -1047,7 +1047,7 @@ class FieldTest(unittest.TestCase):
         BlogPost.drop_collection()
 
     def test_list_assignment(self):
-        """Ensure that list field element assignment and slicing work 
+        """Ensure that list field element assignment and slicing work
         """
         class BlogPost(Document):
             info = ListField()
@@ -1057,12 +1057,12 @@ class FieldTest(unittest.TestCase):
         post = BlogPost()
         post.info = ['e1', 'e2', 3, '4', 5]
         post.save()
-        
+
         post.info[0] = 1
         post.save()
         post.reload()
         self.assertEqual(post.info[0], 1)
-        
+
         post.info[1:3] = ['n2', 'n3']
         post.save()
         post.reload()
@@ -1209,7 +1209,7 @@ class FieldTest(unittest.TestCase):
         self.assertEqual(simple.widgets, [4])
 
     def test_list_field_with_negative_indices(self):
-        
+
         class Simple(Document):
             widgets = ListField()
 
@@ -1823,7 +1823,7 @@ class FieldTest(unittest.TestCase):
                                'parent': "50a234ea469ac1eda42d347d"})
         mongoed = p1.to_mongo()
         self.assertTrue(isinstance(mongoed['parent'], ObjectId))
-        
+
     def test_cached_reference_field_get_and_save(self):
         """
         Tests #1047: CachedReferenceField creates DBRefs on to_python, but can't save them on to_mongo
@@ -1835,11 +1835,11 @@ class FieldTest(unittest.TestCase):
         class Ocorrence(Document):
             person = StringField()
             animal = CachedReferenceField(Animal)
-        
+
         Animal.drop_collection()
         Ocorrence.drop_collection()
-        
-        Ocorrence(person="testte", 
+
+        Ocorrence(person="testte",
                   animal=Animal(name="Leopard", tag="heavy").save()).save()
         p = Ocorrence.objects.get()
         p.person = 'new_testte'
@@ -2810,6 +2810,38 @@ class FieldTest(unittest.TestCase):
         Post.drop_collection()
         User.drop_collection()
 
+    def test_generic_reference_filter_by_dbref(self):
+        """Ensure we can search for a specific generic reference by
+        providing its ObjectId.
+        """
+        class Doc(Document):
+            ref = GenericReferenceField()
+
+        Doc.drop_collection()
+
+        doc1 = Doc.objects.create()
+        doc2 = Doc.objects.create(ref=doc1)
+
+        doc = Doc.objects.get(ref=DBRef('doc', doc1.pk))
+        self.assertEqual(doc, doc2)
+
+    def test_generic_reference_filter_by_objectid(self):
+        """Ensure we can search for a specific generic reference by
+        providing its DBRef.
+        """
+        class Doc(Document):
+            ref = GenericReferenceField()
+
+        Doc.drop_collection()
+
+        doc1 = Doc.objects.create()
+        doc2 = Doc.objects.create(ref=doc1)
+
+        self.assertTrue(isinstance(doc1.pk, ObjectId))
+
+        doc = Doc.objects.get(ref=doc1.pk)
+        self.assertEqual(doc, doc2)
+
     def test_binary_fields(self):
         """Ensure that binary fields can be stored and retrieved.
         """
@@ -3001,28 +3033,32 @@ class FieldTest(unittest.TestCase):
                 ('S', 'Small'), ('M', 'Medium'), ('L', 'Large'),
                 ('XL', 'Extra Large'), ('XXL', 'Extra Extra Large')))
             style = StringField(max_length=3, choices=(
-                ('S', 'Small'), ('B', 'Baggy'), ('W', 'wide')), default='S')
+                ('S', 'Small'), ('B', 'Baggy'), ('W', 'Wide')), default='W')
 
         Shirt.drop_collection()
 
-        shirt = Shirt()
+        shirt1 = Shirt()
+        shirt2 = Shirt()
 
-        self.assertEqual(shirt.get_size_display(), None)
-        self.assertEqual(shirt.get_style_display(), 'Small')
+        # Make sure get_<field>_display returns the default value (or None)
+        self.assertEqual(shirt1.get_size_display(), None)
+        self.assertEqual(shirt1.get_style_display(), 'Wide')
 
-        shirt.size = "XXL"
-        shirt.style = "B"
-        self.assertEqual(shirt.get_size_display(), 'Extra Extra Large')
-        self.assertEqual(shirt.get_style_display(), 'Baggy')
+        shirt1.size = 'XXL'
+        shirt1.style = 'B'
+        shirt2.size = 'M'
+        shirt2.style = 'S'
+        self.assertEqual(shirt1.get_size_display(), 'Extra Extra Large')
+        self.assertEqual(shirt1.get_style_display(), 'Baggy')
+        self.assertEqual(shirt2.get_size_display(), 'Medium')
+        self.assertEqual(shirt2.get_style_display(), 'Small')
 
         # Set as Z - an invalid choice
-        shirt.size = "Z"
-        shirt.style = "Z"
-        self.assertEqual(shirt.get_size_display(), 'Z')
-        self.assertEqual(shirt.get_style_display(), 'Z')
-        self.assertRaises(ValidationError, shirt.validate)
-
-        Shirt.drop_collection()
+        shirt1.size = 'Z'
+        shirt1.style = 'Z'
+        self.assertEqual(shirt1.get_size_display(), 'Z')
+        self.assertEqual(shirt1.get_style_display(), 'Z')
+        self.assertRaises(ValidationError, shirt1.validate)
 
     def test_simple_choices_validation(self):
         """Ensure that value is in a container of allowed values.

tests/queryset/queryset.py

@@ -1,28 +1,23 @@
 # -*- coding: utf-8 -*-
 
-import sys
-sys.path[0:0] = [""]
-
+import datetime
 import unittest
 import uuid
+
+from bson import DBRef, ObjectId
 from nose.plugins.skip import SkipTest
-
-from datetime import datetime, timedelta
-
 import pymongo
 from pymongo.errors import ConfigurationError
 from pymongo.read_preferences import ReadPreference
 
-from bson import ObjectId, DBRef
 
 from mongoengine import *
 from mongoengine.connection import get_connection, get_db
-from mongoengine.python_support import PY3, IS_PYMONGO_3
 from mongoengine.context_managers import query_counter, switch_db
-from mongoengine.queryset import (QuerySet, QuerySetManager,
-                                  MultipleObjectsReturned, DoesNotExist,
-                                  queryset_manager)
 from mongoengine.errors import InvalidQueryError
+from mongoengine.python_support import IS_PYMONGO_3, PY3
+from mongoengine.queryset import (DoesNotExist, MultipleObjectsReturned,
+                                  QuerySet, QuerySetManager, queryset_manager)
 
 __all__ = ("QuerySetTest",)
 
@@ -184,12 +179,14 @@ class QuerySetTest(unittest.TestCase):
 
         self.assertEqual(self.Person.objects.count(), 55)
         self.assertEqual("Person object", "%s" % self.Person.objects[0])
-        self.assertEqual(
-            "[<Person: Person object>, <Person: Person object>]",  "%s" % self.Person.objects[1:3])
-        self.assertEqual(
-            "[<Person: Person object>, <Person: Person object>]",  "%s" % self.Person.objects[51:53])
+        self.assertEqual("[<Person: Person object>, <Person: Person object>]",
+                         "%s" % self.Person.objects[1:3])
+        self.assertEqual("[<Person: Person object>, <Person: Person object>]",
+                         "%s" % self.Person.objects[51:53])
+
         # Test only after limit
         self.assertEqual(self.Person.objects().limit(2).only('name')[0].age, None)
+
         # Test only after skip
         self.assertEqual(self.Person.objects().skip(2).only('name')[0].age, None)
 
@@ -287,6 +284,9 @@ class QuerySetTest(unittest.TestCase):
         blog = Blog.objects(posts__0__comments__0__name='testa').get()
         self.assertEqual(blog, blog1)
 
+        blog = Blog.objects(posts__0__comments__0__name='testb').get()
+        self.assertEqual(blog, blog2)
+
         query = Blog.objects(posts__1__comments__1__name='testb')
         self.assertEqual(query.count(), 2)
 
@@ -337,9 +337,36 @@ class QuerySetTest(unittest.TestCase):
         query = query.filter(boolfield=True)
         self.assertEqual(query.count(), 1)
 
+    def test_batch_size(self):
+        """Ensure that batch_size works."""
+        class A(Document):
+            s = StringField()
+
+        A.drop_collection()
+
+        for i in range(100):
+            A.objects.create(s=str(i))
+
+        # test iterating over the result set
+        cnt = 0
+        for a in A.objects.batch_size(10):
+            cnt += 1
+        self.assertEqual(cnt, 100)
+
+        # test chaining
+        qs = A.objects.all()
+        qs = qs.limit(10).batch_size(20).skip(91)
+        cnt = 0
+        for a in qs:
+            cnt += 1
+        self.assertEqual(cnt, 9)
+
+        # test invalid batch size
+        qs = A.objects.batch_size(-1)
+        self.assertRaises(ValueError, lambda: list(qs))
+
     def test_update_write_concern(self):
         """Test that passing write_concern works"""
-
         self.Person.drop_collection()
 
         write_concern = {"fsync": True}
@@ -633,39 +660,39 @@ class QuerySetTest(unittest.TestCase):
         self.assertRaises(ValidationError, Doc.objects().update, dt_f="datetime", upsert=True)
         self.assertRaises(ValidationError, Doc.objects().update, ed_f__str_f=1, upsert=True)
 
-    def test_update_related_models( self ):
-            class TestPerson( Document ):
+    def test_update_related_models(self):
+            class TestPerson(Document):
                 name = StringField()
 
-            class TestOrganization( Document ):
+            class TestOrganization(Document):
                 name = StringField()
-                owner = ReferenceField( TestPerson )
+                owner = ReferenceField(TestPerson)
 
             TestPerson.drop_collection()
             TestOrganization.drop_collection()
 
-            p = TestPerson( name='p1' )
+            p = TestPerson(name='p1')
             p.save()
-            o = TestOrganization( name='o1' )
+            o = TestOrganization(name='o1')
             o.save()
 
             o.owner = p
             p.name = 'p2'
 
-            self.assertEqual( o._get_changed_fields(), [ 'owner' ] )
-            self.assertEqual( p._get_changed_fields(), [ 'name' ] )
+            self.assertEqual(o._get_changed_fields(), ['owner'])
+            self.assertEqual(p._get_changed_fields(), ['name'])
 
             o.save()
 
-            self.assertEqual( o._get_changed_fields(), [] )
-            self.assertEqual( p._get_changed_fields(), [ 'name' ] ) # Fails; it's empty
+            self.assertEqual(o._get_changed_fields(), [])
+            self.assertEqual(p._get_changed_fields(), ['name'])  # Fails; it's empty
 
             # This will do NOTHING at all, even though we changed the name
             p.save()
 
             p.reload()
 
-            self.assertEqual( p.name, 'p2' ) # Fails; it's still `p1`
+            self.assertEqual(p.name, 'p2')  # Fails; it's still `p1`
 
     def test_upsert(self):
         self.Person.drop_collection()
@@ -694,7 +721,6 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual(30, bobby.age)
         self.assertEqual(bob.id, bobby.id)
 
-
     def test_set_on_insert(self):
         self.Person.drop_collection()
 
@@ -1113,24 +1139,29 @@ class QuerySetTest(unittest.TestCase):
         blog_2.save()
         blog_3.save()
 
-        blog_post_1 = BlogPost(blog=blog_1, title="Blog Post #1",
-                               is_published=True,
-                               published_date=datetime(2010, 1, 5, 0, 0, 0))
-        blog_post_2 = BlogPost(blog=blog_2, title="Blog Post #2",
-                               is_published=True,
-                               published_date=datetime(2010, 1, 6, 0, 0, 0))
-        blog_post_3 = BlogPost(blog=blog_3, title="Blog Post #3",
-                               is_published=True,
-                               published_date=datetime(2010, 1, 7, 0, 0, 0))
-
-        blog_post_1.save()
-        blog_post_2.save()
-        blog_post_3.save()
+        BlogPost.objects.create(
+            blog=blog_1,
+            title="Blog Post #1",
+            is_published=True,
+            published_date=datetime.datetime(2010, 1, 5, 0, 0, 0)
+        )
+        BlogPost.objects.create(
+            blog=blog_2,
+            title="Blog Post #2",
+            is_published=True,
+            published_date=datetime.datetime(2010, 1, 6, 0, 0, 0)
+        )
+        BlogPost.objects.create(
+            blog=blog_3,
+            title="Blog Post #3",
+            is_published=True,
+            published_date=datetime.datetime(2010, 1, 7, 0, 0, 0)
+        )
 
         # find all published blog posts before 2010-01-07
         published_posts = BlogPost.published()
         published_posts = published_posts.filter(
-            published_date__lt=datetime(2010, 1, 7, 0, 0, 0))
+            published_date__lt=datetime.datetime(2010, 1, 7, 0, 0, 0))
         self.assertEqual(published_posts.count(), 2)
 
         blog_posts = BlogPost.objects
@@ -1161,16 +1192,18 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
-        blog_post_1 = BlogPost(title="Blog Post #1",
-                               published_date=datetime(2010, 1, 5, 0, 0, 0))
-        blog_post_2 = BlogPost(title="Blog Post #2",
-                               published_date=datetime(2010, 1, 6, 0, 0, 0))
-        blog_post_3 = BlogPost(title="Blog Post #3",
-                               published_date=datetime(2010, 1, 7, 0, 0, 0))
-
-        blog_post_1.save()
-        blog_post_2.save()
-        blog_post_3.save()
+        blog_post_1 = BlogPost.objects.create(
+            title="Blog Post #1",
+            published_date=datetime.datetime(2010, 1, 5, 0, 0, 0)
+        )
+        blog_post_2 = BlogPost.objects.create(
+            title="Blog Post #2",
+            published_date=datetime.datetime(2010, 1, 6, 0, 0, 0)
+        )
+        blog_post_3 = BlogPost.objects.create(
+            title="Blog Post #3",
+            published_date=datetime.datetime(2010, 1, 7, 0, 0, 0)
+        )
 
         # get the "first" BlogPost using default ordering
         # from BlogPost.meta.ordering
@@ -1219,7 +1252,7 @@ class QuerySetTest(unittest.TestCase):
             }
 
         BlogPost.objects.create(
-            title='whatever', published_date=datetime.utcnow())
+            title='whatever', published_date=datetime.datetime.utcnow())
 
         with db_ops_tracker() as q:
             BlogPost.objects.get(title='whatever')
@@ -1233,7 +1266,8 @@ class QuerySetTest(unittest.TestCase):
             self.assertFalse('$orderby' in q.get_ops()[0]['query'])
 
     def test_find_embedded(self):
-        """Ensure that an embedded document is properly returned from a query.
+        """Ensure that an embedded document is properly returned from
+        a query.
         """
         class User(EmbeddedDocument):
             name = StringField()
@@ -1244,16 +1278,31 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
-        post = BlogPost(content='Had a good coffee today...')
-        post.author = User(name='Test User')
-        post.save()
+        BlogPost.objects.create(
+            author=User(name='Test User'),
+            content='Had a good coffee today...'
+        )
 
         result = BlogPost.objects.first()
         self.assertTrue(isinstance(result.author, User))
         self.assertEqual(result.author.name, 'Test User')
 
+    def test_find_empty_embedded(self):
+        """Ensure that you can save and find an empty embedded document."""
+        class User(EmbeddedDocument):
+            name = StringField()
+
+        class BlogPost(Document):
+            content = StringField()
+            author = EmbeddedDocumentField(User)
+
         BlogPost.drop_collection()
 
+        BlogPost.objects.create(content='Anonymous post...')
+
+        result = BlogPost.objects.get(author=None)
+        self.assertEqual(result.author, None)
+
     def test_find_dict_item(self):
         """Ensure that DictField items may be found.
         """
@@ -2082,18 +2131,22 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
-        blog_post_3 = BlogPost(title="Blog Post #3",
-                               published_date=datetime(2010, 1, 6, 0, 0, 0))
-        blog_post_2 = BlogPost(title="Blog Post #2",
-                               published_date=datetime(2010, 1, 5, 0, 0, 0))
-        blog_post_4 = BlogPost(title="Blog Post #4",
-                               published_date=datetime(2010, 1, 7, 0, 0, 0))
-        blog_post_1 = BlogPost(title="Blog Post #1", published_date=None)
-
-        blog_post_3.save()
-        blog_post_1.save()
-        blog_post_4.save()
-        blog_post_2.save()
+        blog_post_3 = BlogPost.objects.create(
+            title="Blog Post #3",
+            published_date=datetime.datetime(2010, 1, 6, 0, 0, 0)
+        )
+        blog_post_2 = BlogPost.objects.create(
+            title="Blog Post #2",
+            published_date=datetime.datetime(2010, 1, 5, 0, 0, 0)
+        )
+        blog_post_4 = BlogPost.objects.create(
+            title="Blog Post #4",
+            published_date=datetime.datetime(2010, 1, 7, 0, 0, 0)
+        )
+        blog_post_1 = BlogPost.objects.create(
+            title="Blog Post #1",
+            published_date=None
+        )
 
         expected = [blog_post_1, blog_post_2, blog_post_3, blog_post_4]
         self.assertSequence(BlogPost.objects.order_by('published_date'),
@@ -2112,16 +2165,18 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
-        blog_post_1 = BlogPost(title="A",
-                               published_date=datetime(2010, 1, 6, 0, 0, 0))
-        blog_post_2 = BlogPost(title="B",
-                               published_date=datetime(2010, 1, 6, 0, 0, 0))
-        blog_post_3 = BlogPost(title="C",
-                               published_date=datetime(2010, 1, 7, 0, 0, 0))
-
-        blog_post_2.save()
-        blog_post_3.save()
-        blog_post_1.save()
+        blog_post_1 = BlogPost.objects.create(
+            title="A",
+            published_date=datetime.datetime(2010, 1, 6, 0, 0, 0)
+        )
+        blog_post_2 = BlogPost.objects.create(
+            title="B",
+            published_date=datetime.datetime(2010, 1, 6, 0, 0, 0)
+        )
+        blog_post_3 = BlogPost.objects.create(
+            title="C",
+            published_date=datetime.datetime(2010, 1, 7, 0, 0, 0)
+        )
 
         qs = BlogPost.objects.order_by('published_date', 'title')
         expected = [blog_post_1, blog_post_2, blog_post_3]
@@ -2187,6 +2242,21 @@ class QuerySetTest(unittest.TestCase):
             a.author.name for a in Author.objects.order_by('-author__age')]
         self.assertEqual(names, ['User A', 'User B', 'User C'])
 
+    def test_comment(self):
+        """Make sure adding a comment to the query works."""
+        class User(Document):
+            age = IntField()
+
+        with db_ops_tracker() as q:
+            adult = (User.objects.filter(age__gte=18)
+                .comment('looking for an adult')
+                .first())
+            ops = q.get_ops()
+            self.assertEqual(len(ops), 1)
+            op = ops[0]
+            self.assertEqual(op['query']['$query'], {'age': {'$gte': 18}})
+            self.assertEqual(op['query']['$comment'], 'looking for an adult')
+
     def test_map_reduce(self):
         """Ensure map/reduce is both mapping and reducing.
         """
@@ -2425,7 +2495,7 @@ class QuerySetTest(unittest.TestCase):
 
         Link.drop_collection()
 
-        now = datetime.utcnow()
+        now = datetime.datetime.utcnow()
 
         # Note: Test data taken from a custom Reddit homepage on
         # Fri, 12 Feb 2010 14:36:00 -0600. Link ordering should
@@ -2434,27 +2504,27 @@ class QuerySetTest(unittest.TestCase):
         Link(title="Google Buzz auto-followed a woman's abusive ex ...",
              up_votes=1079,
              down_votes=553,
-             submitted=now - timedelta(hours=4)).save()
+             submitted=now - datetime.timedelta(hours=4)).save()
         Link(title="We did it! Barbie is a computer engineer.",
              up_votes=481,
              down_votes=124,
-             submitted=now - timedelta(hours=2)).save()
+             submitted=now - datetime.timedelta(hours=2)).save()
         Link(title="This Is A Mosquito Getting Killed By A Laser",
              up_votes=1446,
              down_votes=530,
-             submitted=now - timedelta(hours=13)).save()
+             submitted=now - datetime.timedelta(hours=13)).save()
         Link(title="Arabic flashcards land physics student in jail.",
              up_votes=215,
              down_votes=105,
-             submitted=now - timedelta(hours=6)).save()
+             submitted=now - datetime.timedelta(hours=6)).save()
         Link(title="The Burger Lab: Presenting, the Flood Burger",
              up_votes=48,
              down_votes=17,
-             submitted=now - timedelta(hours=5)).save()
+             submitted=now - datetime.timedelta(hours=5)).save()
         Link(title="How to see polarization with the naked eye",
              up_votes=74,
              down_votes=13,
-             submitted=now - timedelta(hours=10)).save()
+             submitted=now - datetime.timedelta(hours=10)).save()
 
         map_f = """
             function() {
@@ -2504,7 +2574,7 @@ class QuerySetTest(unittest.TestCase):
 
         # provide the reddit epoch (used for ranking) as a variable available
         # to all phases of the map/reduce operation: map, reduce, and finalize.
-        reddit_epoch = mktime(datetime(2005, 12, 8, 7, 46, 43).timetuple())
+        reddit_epoch = mktime(datetime.datetime(2005, 12, 8, 7, 46, 43).timetuple())
         scope = {'reddit_epoch': reddit_epoch}
 
         # run a map/reduce operation across all links. ordering is set
@@ -2826,6 +2896,34 @@ 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()
@@ -3096,13 +3194,11 @@ class QuerySetTest(unittest.TestCase):
         mark_twain = Author(name="Mark Twain")
         john_tolkien = Author(name="John Ronald Reuel Tolkien")
 
-        book = Book(title="Tom Sawyer", authors=[mark_twain]).save()
-        book = Book(
-            title="The Lord of the Rings", authors=[john_tolkien]).save()
-        book = Book(
-            title="The Stories", authors=[mark_twain, john_tolkien]).save()
-        authors = Book.objects.distinct("authors")
+        Book.objects.create(title="Tom Sawyer", authors=[mark_twain])
+        Book.objects.create(title="The Lord of the Rings", authors=[john_tolkien])
+        Book.objects.create(title="The Stories", authors=[mark_twain, john_tolkien])
 
+        authors = Book.objects.distinct("authors")
         self.assertEqual(authors, [mark_twain, john_tolkien])
 
     def test_distinct_ListField_EmbeddedDocumentField_EmbeddedDocumentField(self):
@@ -3132,17 +3228,14 @@ class QuerySetTest(unittest.TestCase):
         mark_twain = Author(name="Mark Twain", country=scotland)
         john_tolkien = Author(name="John Ronald Reuel Tolkien", country=tibet)
 
-        book = Book(title="Tom Sawyer", authors=[mark_twain]).save()
-        book = Book(
-            title="The Lord of the Rings", authors=[john_tolkien]).save()
-        book = Book(
-            title="The Stories", authors=[mark_twain, john_tolkien]).save()
-        country_list = Book.objects.distinct("authors.country")
+        Book.objects.create(title="Tom Sawyer", authors=[mark_twain])
+        Book.objects.create(title="The Lord of the Rings", authors=[john_tolkien])
+        Book.objects.create(title="The Stories", authors=[mark_twain, john_tolkien])
 
+        country_list = Book.objects.distinct("authors.country")
         self.assertEqual(country_list, [scotland, tibet])
 
         continent_list = Book.objects.distinct("authors.country.continent")
-
         self.assertEqual(continent_list, [europe, asia])
 
     def test_distinct_ListField_ReferenceField(self):
@@ -3174,7 +3267,7 @@ class QuerySetTest(unittest.TestCase):
         class BlogPost(Document):
             tags = ListField(StringField())
             deleted = BooleanField(default=False)
-            date = DateTimeField(default=datetime.now)
+            date = DateTimeField(default=datetime.datetime.now)
 
             @queryset_manager
             def objects(cls, qryset):
@@ -3997,14 +4090,14 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual(
             "A0", "%s" % self.Person.objects.scalar('name').order_by('name')[0])
         if PY3:
-            self.assertEqual(
-                "['A1', 'A2']",  "%s" % self.Person.objects.order_by('age').scalar('name')[1:3])
-            self.assertEqual("['A51', 'A52']",  "%s" % self.Person.objects.order_by(
+            self.assertEqual("['A1', 'A2']", "%s" % self.Person.objects.order_by(
+                'age').scalar('name')[1:3])
+            self.assertEqual("['A51', 'A52']", "%s" % self.Person.objects.order_by(
                 'age').scalar('name')[51:53])
         else:
-            self.assertEqual("[u'A1', u'A2']",  "%s" % self.Person.objects.order_by(
+            self.assertEqual("[u'A1', u'A2']", "%s" % self.Person.objects.order_by(
                 'age').scalar('name')[1:3])
-            self.assertEqual("[u'A51', u'A52']",  "%s" % self.Person.objects.order_by(
+            self.assertEqual("[u'A51', u'A52']", "%s" % self.Person.objects.order_by(
                 'age').scalar('name')[51:53])
 
         # with_id and in_bulk
@@ -4013,12 +4106,12 @@ class QuerySetTest(unittest.TestCase):
                          self.Person.objects.scalar('name').with_id(person.id))
 
         pks = self.Person.objects.order_by('age').scalar('pk')[1:3]
+        names = self.Person.objects.scalar('name').in_bulk(list(pks)).values()
         if PY3:
-            self.assertEqual("['A1', 'A2']",  "%s" % sorted(
-                self.Person.objects.scalar('name').in_bulk(list(pks)).values()))
+            expected = "['A1', 'A2']"
         else:
-            self.assertEqual("[u'A1', u'A2']",  "%s" % sorted(
-                self.Person.objects.scalar('name').in_bulk(list(pks)).values()))
+            expected = "[u'A1', u'A2']"
+        self.assertEqual(expected, "%s" % sorted(names))
 
     def test_elem_match(self):
         class Foo(EmbeddedDocument):
@@ -4115,7 +4208,7 @@ class QuerySetTest(unittest.TestCase):
             txt = StringField()
 
             meta = {
-                'indexes': [ 'txt' ]
+                'indexes': ['txt']
             }
 
         Bar.drop_collection()
@@ -4130,49 +4223,49 @@ class QuerySetTest(unittest.TestCase):
 
         # read_preference as a kwarg
         bars = Bar.objects(read_preference=ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
         # read_preference as a query set method
         bars = Bar.objects.read_preference(ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
         # read_preference after skip
         bars = Bar.objects.skip(1) \
             .read_preference(ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
         # read_preference after limit
         bars = Bar.objects.limit(1) \
             .read_preference(ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
         # read_preference after order_by
         bars = Bar.objects.order_by('txt') \
             .read_preference(ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
         # read_preference after hint
         bars = Bar.objects.hint([('txt', 1)]) \
             .read_preference(ReadPreference.SECONDARY_PREFERRED)
-        self.assertEqual(
-            bars._read_preference, ReadPreference.SECONDARY_PREFERRED)
+        self.assertEqual(bars._read_preference,
+                         ReadPreference.SECONDARY_PREFERRED)
         self.assertEqual(bars._cursor._Cursor__read_preference,
-            ReadPreference.SECONDARY_PREFERRED)
+                         ReadPreference.SECONDARY_PREFERRED)
 
     def test_json_simple(self):
 
@@ -4208,7 +4301,7 @@ class QuerySetTest(unittest.TestCase):
             int_field = IntField(default=1)
             float_field = FloatField(default=1.1)
             boolean_field = BooleanField(default=True)
-            datetime_field = DateTimeField(default=datetime.now)
+            datetime_field = DateTimeField(default=datetime.datetime.now)
             embedded_document_field = EmbeddedDocumentField(
                 EmbeddedDoc, default=lambda: EmbeddedDoc())
             list_field = ListField(default=lambda: [1, 2, 3])
@@ -4218,7 +4311,7 @@ class QuerySetTest(unittest.TestCase):
                 Simple, default=lambda: Simple().save())
             map_field = MapField(IntField(), default=lambda: {"simple": 1})
             decimal_field = DecimalField(default=1.0)
-            complex_datetime_field = ComplexDateTimeField(default=datetime.now)
+            complex_datetime_field = ComplexDateTimeField(default=datetime.datetime.now)
             url_field = URLField(default="http://mongoengine.org")
             dynamic_field = DynamicField(default=1)
             generic_reference_field = GenericReferenceField(
@@ -4565,8 +4658,7 @@ class QuerySetTest(unittest.TestCase):
         B.drop_collection()
 
         a = A.objects.create(id='custom_id')
-
-        b = B.objects.create(a=a)
+        B.objects.create(a=a)
 
         self.assertEqual(B.objects.count(), 1)
         self.assertEqual(B.objects.get(a=a).a, a)
@@ -4826,6 +4918,56 @@ class QuerySetTest(unittest.TestCase):
 
         self.assertEqual(1, Doc.objects(item__type__="axe").count())
 
+    def test_len_during_iteration(self):
+        """Tests that calling len on a queyset during iteration doesn't
+        stop paging.
+        """
+        class Data(Document):
+            pass
+
+        for i in xrange(300):
+            Data().save()
+
+        records = Data.objects.limit(250)
+
+        # This should pull all 250 docs from mongo and populate the result
+        # cache
+        len(records)
+
+        # Assert that iterating over documents in the qs touches every
+        # document even if we call len(qs) midway through the iteration.
+        for i, r in enumerate(records):
+            if i == 58:
+                len(records)
+        self.assertEqual(i, 249)
+
+        # Assert the same behavior is true even if we didn't pre-populate the
+        # result cache.
+        records = Data.objects.limit(250)
+        for i, r in enumerate(records):
+            if i == 58:
+                len(records)
+        self.assertEqual(i, 249)
+
+    def test_iteration_within_iteration(self):
+        """You should be able to reliably iterate over all the documents
+        in a given queryset even if there are multiple iterations of it
+        happening at the same time.
+        """
+        class Data(Document):
+            pass
+
+        for i in xrange(300):
+            Data().save()
+
+        qs = Data.objects.limit(250)
+        for i, doc in enumerate(qs):
+            for j, doc2 in enumerate(qs):
+                pass
+
+        self.assertEqual(i, 249)
+        self.assertEqual(j, 249)
+
 
 if __name__ == '__main__':
     unittest.main()

tests/queryset/transform.py

@@ -1,11 +1,7 @@
-import sys
-sys.path[0:0] = [""]
-
 import unittest
 
 from mongoengine import *
-from mongoengine.queryset import Q
-from mongoengine.queryset import transform
+from mongoengine.queryset import Q, transform
 
 __all__ = ("TransformTest",)
 
@@ -41,8 +37,8 @@ class TransformTest(unittest.TestCase):
         DicDoc.drop_collection()
         Doc.drop_collection()
 
+        DicDoc().save()
         doc = Doc().save()
-        dic_doc = DicDoc().save()
 
         for k, v in (("set", "$set"), ("set_on_insert", "$setOnInsert"), ("push", "$push")):
             update = transform.update(DicDoc, **{"%s__dictField__test" % k: doc})
@@ -55,7 +51,6 @@ class TransformTest(unittest.TestCase):
         update = transform.update(DicDoc, pull__dictField__test=doc)
         self.assertTrue(isinstance(update["$pull"]["dictField"]["test"], dict))
 
-
     def test_query_field_name(self):
         """Ensure that the correct field name is used when querying.
         """
@@ -156,26 +151,33 @@ class TransformTest(unittest.TestCase):
         class Doc(Document):
             meta = {'allow_inheritance': False}
 
-        raw_query = Doc.objects(__raw__={'deleted': False,
-                                'scraped': 'yes',
-                                '$nor': [{'views.extracted': 'no'},
-                                         {'attachments.views.extracted':'no'}]
-                                })._query
+        raw_query = Doc.objects(__raw__={
+            'deleted': False,
+            'scraped': 'yes',
+            '$nor': [
+                {'views.extracted': 'no'},
+                {'attachments.views.extracted': 'no'}
+            ]
+        })._query
 
-        expected = {'deleted': False, 'scraped': 'yes',
-                    '$nor': [{'views.extracted': 'no'},
-                             {'attachments.views.extracted': 'no'}]}
-        self.assertEqual(expected, raw_query)
+        self.assertEqual(raw_query, {
+            'deleted': False,
+            'scraped': 'yes',
+            '$nor': [
+                {'views.extracted': 'no'},
+                {'attachments.views.extracted': 'no'}
+            ]
+        })
 
     def test_geojson_PointField(self):
         class Location(Document):
             loc = PointField()
 
         update = transform.update(Location, set__loc=[1, 2])
-        self.assertEqual(update, {'$set': {'loc': {"type": "Point", "coordinates": [1,2]}}})
+        self.assertEqual(update, {'$set': {'loc': {"type": "Point", "coordinates": [1, 2]}}})
 
-        update = transform.update(Location, set__loc={"type": "Point", "coordinates": [1,2]})
-        self.assertEqual(update, {'$set': {'loc': {"type": "Point", "coordinates": [1,2]}}})
+        update = transform.update(Location, set__loc={"type": "Point", "coordinates": [1, 2]})
+        self.assertEqual(update, {'$set': {'loc': {"type": "Point", "coordinates": [1, 2]}}})
 
     def test_geojson_LineStringField(self):
         class Location(Document):
@@ -238,5 +240,6 @@ class TransformTest(unittest.TestCase):
         events = Event.objects(location__within=box)
         self.assertRaises(InvalidQueryError, lambda: events.count())
 
+
 if __name__ == '__main__':
     unittest.main()

tests/queryset/visitor.py

@@ -1,14 +1,12 @@
-import sys
-sys.path[0:0] = [""]
-
+import datetime
+import re
 import unittest
 
 from bson import ObjectId
-from datetime import datetime
 
 from mongoengine import *
-from mongoengine.queryset import Q
 from mongoengine.errors import InvalidQueryError
+from mongoengine.queryset import Q
 
 __all__ = ("QTest",)
 
@@ -132,12 +130,12 @@ class QTest(unittest.TestCase):
         TestDoc(x=10).save()
         TestDoc(y=True).save()
 
-        self.assertEqual(query,
-        {'$and': [
-            {'$or': [{'x': {'$gt': 0}}, {'x': {'$exists': False}}]},
-            {'$or': [{'x': {'$lt': 100}}, {'y': True}]}
-        ]})
-
+        self.assertEqual(query, {
+            '$and': [
+                {'$or': [{'x': {'$gt': 0}}, {'x': {'$exists': False}}]},
+                {'$or': [{'x': {'$lt': 100}}, {'y': True}]}
+            ]
+        })
         self.assertEqual(2, TestDoc.objects(q1 & q2).count())
 
     def test_or_and_or_combination(self):
@@ -157,15 +155,14 @@ class QTest(unittest.TestCase):
         q2 = (Q(x__lt=100) & (Q(y=False) | Q(y__exists=False)))
         query = (q1 | q2).to_query(TestDoc)
 
-        self.assertEqual(query,
-            {'$or': [
+        self.assertEqual(query, {
+            '$or': [
                 {'$and': [{'x': {'$gt': 0}},
                           {'$or': [{'y': True}, {'y': {'$exists': False}}]}]},
                 {'$and': [{'x': {'$lt': 100}},
                           {'$or': [{'y': False}, {'y': {'$exists': False}}]}]}
-            ]}
-        )
-
+            ]
+        })
         self.assertEqual(2, TestDoc.objects(q1 | q2).count())
 
     def test_multiple_occurence_in_field(self):
@@ -215,19 +212,19 @@ class QTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
-        post1 = BlogPost(title='Test 1', publish_date=datetime(2010, 1, 8), published=False)
+        post1 = BlogPost(title='Test 1', publish_date=datetime.datetime(2010, 1, 8), published=False)
         post1.save()
 
-        post2 = BlogPost(title='Test 2', publish_date=datetime(2010, 1, 15), published=True)
+        post2 = BlogPost(title='Test 2', publish_date=datetime.datetime(2010, 1, 15), published=True)
         post2.save()
 
         post3 = BlogPost(title='Test 3', published=True)
         post3.save()
 
-        post4 = BlogPost(title='Test 4', publish_date=datetime(2010, 1, 8))
+        post4 = BlogPost(title='Test 4', publish_date=datetime.datetime(2010, 1, 8))
         post4.save()
 
-        post5 = BlogPost(title='Test 1', publish_date=datetime(2010, 1, 15))
+        post5 = BlogPost(title='Test 1', publish_date=datetime.datetime(2010, 1, 15))
         post5.save()
 
         post6 = BlogPost(title='Test 1', published=False)
@@ -250,7 +247,7 @@ class QTest(unittest.TestCase):
         self.assertTrue(all(obj.id in posts for obj in published_posts))
 
         # Check Q object combination
-        date = datetime(2010, 1, 10)
+        date = datetime.datetime(2010, 1, 10)
         q = BlogPost.objects(Q(publish_date__lte=date) | Q(published=True))
         posts = [post.id for post in q]
 
@@ -273,8 +270,10 @@ class QTest(unittest.TestCase):
         # Test invalid query objs
         def wrong_query_objs():
             self.Person.objects('user1')
+
         def wrong_query_objs_filter():
             self.Person.objects('user1')
+
         self.assertRaises(InvalidQueryError, wrong_query_objs)
         self.assertRaises(InvalidQueryError, wrong_query_objs_filter)
 
@@ -284,7 +283,6 @@ class QTest(unittest.TestCase):
         person = self.Person(name='Guido van Rossum')
         person.save()
 
-        import re
         obj = self.Person.objects(Q(name=re.compile('^Gui'))).first()
         self.assertEqual(obj, person)
         obj = self.Person.objects(Q(name=re.compile('^gui'))).first()

tests/test_connection.py

@@ -174,19 +174,9 @@ class ConnectionTest(unittest.TestCase):
         c.mongoenginetest.system.users.remove({})
 
     def test_connect_uri_without_db(self):
-        """Ensure connect() method works properly with uri's without database_name
+        """Ensure connect() method works properly if the URI doesn't
+        include a database name.
         """
-        c = connect(db='mongoenginetest', alias='admin')
-        c.admin.system.users.remove({})
-        c.mongoenginetest.system.users.remove({})
-
-        c.admin.add_user("admin", "password")
-        c.admin.authenticate("admin", "password")
-        c.mongoenginetest.add_user("username", "password")
-
-        if not IS_PYMONGO_3:
-            self.assertRaises(ConnectionError, connect, "testdb_uri_bad", host='mongodb://test:password@localhost')
-
         connect("mongoenginetest", host='mongodb://localhost/')
 
         conn = get_connection()
@@ -196,8 +186,31 @@ class ConnectionTest(unittest.TestCase):
         self.assertTrue(isinstance(db, pymongo.database.Database))
         self.assertEqual(db.name, 'mongoenginetest')
 
-        c.admin.system.users.remove({})
-        c.mongoenginetest.system.users.remove({})
+    def test_connect_uri_default_db(self):
+        """Ensure connect() defaults to the right database name if
+        the URI and the database_name don't explicitly specify it.
+        """
+        connect(host='mongodb://localhost/')
+
+        conn = get_connection()
+        self.assertTrue(isinstance(conn, pymongo.mongo_client.MongoClient))
+
+        db = get_db()
+        self.assertTrue(isinstance(db, pymongo.database.Database))
+        self.assertEqual(db.name, 'test')
+
+    def test_uri_without_credentials_doesnt_override_conn_settings(self):
+        """Ensure connect() uses the username & password params if the URI
+        doesn't explicitly specify them.
+        """
+        c = connect(host='mongodb://localhost/mongoenginetest',
+                    username='user',
+                    password='pass')
+
+        # OperationFailure means that mongoengine attempted authentication
+        # w/ the provided username/password and failed - that's the desired
+        # behavior. If the MongoDB URI would override the credentials
+        self.assertRaises(OperationFailure, get_db)
 
     def test_connect_uri_with_authsource(self):
         """Ensure that the connect() method works well with

tests/test_datastructures.py

@@ -1,5 +1,6 @@
 import unittest
-from mongoengine.base.datastructures import StrictDict, SemiStrictDict 
+
+from mongoengine.base.datastructures import StrictDict, SemiStrictDict
 
 
 class TestStrictDict(unittest.TestCase):
@@ -13,9 +14,17 @@ class TestStrictDict(unittest.TestCase):
         d = self.dtype(a=1, b=1, c=1)
         self.assertEqual((d.a, d.b, d.c), (1, 1, 1))
 
+    def test_repr(self):
+        d = self.dtype(a=1, b=2, c=3)
+        self.assertEqual(repr(d), '{"a": 1, "b": 2, "c": 3}')
+
+        # make sure quotes are escaped properly
+        d = self.dtype(a='"', b="'", c="")
+        self.assertEqual(repr(d), '{"a": \'"\', "b": "\'", "c": \'\'}')
+
     def test_init_fails_on_nonexisting_attrs(self):
         self.assertRaises(AttributeError, lambda: self.dtype(a=1, b=2, d=3))
-        
+
     def test_eq(self):
         d = self.dtype(a=1, b=1, c=1)
         dd = self.dtype(a=1, b=1, c=1)
@@ -24,7 +33,7 @@ class TestStrictDict(unittest.TestCase):
         g = self.strict_dict_class(("a", "b", "c", "d"))(a=1, b=1, c=1, d=1)
         h = self.strict_dict_class(("a", "c", "b"))(a=1, b=1, c=1)
         i = self.strict_dict_class(("a", "c", "b"))(a=1, b=1, c=2)
-        
+
         self.assertEqual(d, dd)
         self.assertNotEqual(d, e)
         self.assertNotEqual(d, f)
@@ -38,19 +47,19 @@ class TestStrictDict(unittest.TestCase):
         d.a = 1
         self.assertEqual(d.a, 1)
         self.assertRaises(AttributeError, lambda: d.b)
-    
+
     def test_setattr_raises_on_nonexisting_attr(self):
         d = self.dtype()
 
         def _f():
             d.x = 1
         self.assertRaises(AttributeError, _f)
-    
+
     def test_setattr_getattr_special(self):
         d = self.strict_dict_class(["items"])
         d.items = 1
         self.assertEqual(d.items, 1)
-    
+
     def test_get(self):
         d = self.dtype(a=1)
         self.assertEqual(d.get('a'), 1)
@@ -88,7 +97,7 @@ class TestSemiSrictDict(TestStrictDict):
     def test_init_succeeds_with_nonexisting_attrs(self):
         d = self.dtype(a=1, b=1, c=1, x=2)
         self.assertEqual((d.a, d.b, d.c, d.x), (1, 1, 1, 2))
-   
+
     def test_iter_with_nonexisting_attrs(self):
         d = self.dtype(a=1, b=1, c=1, x=2)
         self.assertEqual(list(d), ['a', 'b', 'c', 'x'])

tox.ini

@@ -1,6 +1,5 @@
 [tox]
-envlist = {py26,py27,py33,py34,py35,pypy,pypy3}-{mg27,mg28}
-#envlist = {py26,py27,py33,py34,pypy,pypy3}-{mg27,mg28,mg30,mgdev}
+envlist = {py26,py27,py33,py34,py35,pypy,pypy3}-{mg27,mg28},flake8
 
 [testenv]
 commands =
@@ -14,3 +13,10 @@ deps =
 setenv =
     PYTHON_EGG_CACHE = {envdir}/python-eggs
 passenv = windir
+
+[testenv:flake8]
+deps =
+    flake8
+    flake8-import-order
+commands =
+   flake8