Fixed set/unset issue with ListFields

mongoengine/base.py

@@ -55,7 +55,7 @@ class BaseField(object):
         """
         return self.to_python(value)
 
-    def prepare_query_value(self, value):
+    def prepare_query_value(self, op, value):
         """Prepare a value that is being used in a query for PyMongo.
         """
         return value
@@ -81,7 +81,7 @@ class ObjectIdField(BaseField):
                 raise ValidationError(e.message)
         return value
 
-    def prepare_query_value(self, value):
+    def prepare_query_value(self, op, value):
         return self.to_mongo(value)
 
     def validate(self, value):

mongoengine/fields.py

@@ -136,7 +136,7 @@ class EmbeddedDocumentField(BaseField):
     def lookup_member(self, member_name):
         return self.document._fields.get(member_name)
 
-    def prepare_query_value(self, value):
+    def prepare_query_value(self, op, value):
         return self.to_mongo(value)
 
 
@@ -166,6 +166,7 @@ class ListField(BaseField):
             referenced_type = self.field.document_type
             # Get value from document instance if available
             value_list = instance._data.get(self.name)
+            if value_list:
                 deref_list = []
                 for value in value_list:
                     # Dereference DBRefs
@@ -197,7 +198,9 @@ class ListField(BaseField):
             raise ValidationError('All items in a list field must be of the '
                                   'specified type')
 
-    def prepare_query_value(self, value):
+    def prepare_query_value(self, op, value):
+        if op in ('set', 'unset'):
+            return [self.field.to_mongo(v) for v in value]
         return self.field.to_mongo(value)
 
     def lookup_member(self, member_name):
@@ -273,7 +276,7 @@ class ReferenceField(BaseField):
         collection = self.document_type._meta['collection']
         return pymongo.dbref.DBRef(collection, id_)
     
-    def prepare_query_value(self, value):
+    def prepare_query_value(self, op, value):
         return self.to_mongo(value)
 
     def validate(self, value):

mongoengine/queryset.py

@@ -284,10 +284,10 @@ class QuerySet(object):
                 # Convert value to proper value
                 field = fields[-1]
                 if op in (None, 'ne', 'gt', 'gte', 'lt', 'lte'):
-                    value = field.prepare_query_value(value)
+                    value = field.prepare_query_value(op, value)
                 elif op in ('in', 'nin', 'all'):
                     # 'in', 'nin' and 'all' require a list of values
-                    value = [field.prepare_query_value(v) for v in value]
+                    value = [field.prepare_query_value(op, v) for v in value]
 
             if op:
                 value = {'$' + op: value}
@@ -487,9 +487,9 @@ class QuerySet(object):
                 # Convert value to proper value
                 field = fields[-1]
                 if op in (None, 'set', 'unset', 'push', 'pull'):
-                    value = field.prepare_query_value(value)
+                    value = field.prepare_query_value(op, value)
                 elif op in ('pushAll', 'pullAll'):
-                    value = [field.prepare_query_value(v) for v in value]
+                    value = [field.prepare_query_value(op, v) for v in value]
 
             key = '.'.join(parts)
 

tests/queryset.py

@@ -594,6 +594,30 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
+    def test_update_value_conversion(self):
+        """Ensure that values used in updates are converted before use.
+        """
+        class Group(Document):
+            members = ListField(ReferenceField(self.Person))
+
+        Group.drop_collection()
+
+        user1 = self.Person(name='user1')
+        user1.save()
+        user2 = self.Person(name='user2')
+        user2.save()
+
+        group = Group()
+        group.save()
+
+        Group.objects(id=group.id).update(set__members=[user1, user2])
+        group.reload()
+
+        self.assertTrue(len(group.members) == 2)
+        self.assertEqual(group.members[0].name, user1.name)
+        self.assertEqual(group.members[1].name, user2.name)
+
+        Group.drop_collection()
 
     def test_types_index(self):
         """Ensure that and index is used when '_types' is being used in a