Added sort method to QuerySet

mongoengine/document.py

@@ -25,7 +25,8 @@ class Document(BaseDocument):
         """Delete the document from the database. This will only take effect
         if the document has been previously saved.
         """
-        self.objects._collection.remove(self.id)
+        object_id = self._fields['id'].to_mongo(self.id)
+        self.__class__.objects(_id=object_id).delete()
 
     @classmethod
     def drop_collection(cls):

mongoengine/queryset.py

@@ -97,6 +97,22 @@ class QuerySet(object):
         """
         self._collection.remove(self._query)
 
+    def sort(self, *keys):
+        """Sort the QuerySet by the keys. The order may be specified by 
+        prepending each of the keys by a + or a -. Ascending order is assumed.
+        """
+        key_list = []
+        for key in keys:
+            direction = pymongo.ASCENDING
+            if key[0] == '-':
+                direction = pymongo.DESCENDING
+            if key[0] in ('-', '+'):
+                key = key[1:]
+            key_list.append((key, direction)) 
+
+        self._cursor.sort(key_list)
+        return self
+
     def __iter__(self):
         return self
 

tests/queryset.py

@@ -137,6 +137,25 @@ class QuerySetTest(unittest.TestCase):
         self.Person.objects.delete()
         self.assertEqual(self.Person.objects.count(), 0)
 
+    def test_sort(self):
+        """Ensure that QuerySets may be sorted.
+        """
+        self.Person(name="User A", age=20).save()
+        self.Person(name="User B", age=40).save()
+        self.Person(name="User C", age=30).save()
+
+        names = [p.name for p in self.Person.objects.sort('-age')]
+        self.assertEqual(names, ['User B', 'User C', 'User A'])
+
+        names = [p.name for p in self.Person.objects.sort('+age')]
+        self.assertEqual(names, ['User A', 'User C', 'User B'])
+
+        names = [p.name for p in self.Person.objects.sort('age')]
+        self.assertEqual(names, ['User A', 'User C', 'User B'])
+        
+        ages = [p.age for p in self.Person.objects.sort('-name')]
+        self.assertEqual(ages, [30, 40, 20])
+
     def tearDown(self):
         self.Person.drop_collection()