Upserting is the only way to ensure docs are saved correctly (#306)

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.8.0
 ================
+- Upserting is the only way to ensure docs are saved correctly (#306)
 - Fixed register_delete_rule inheritance issue
 - Fix cloning of sliced querysets (#303)
 - Fixed update_one write concern (#302)

mongoengine/document.py

@@ -231,7 +231,6 @@ class Document(BaseDocument):
                             return not updated
                     return created
 
-                upsert = self._created
                 update_query = {}
 
                 if updates:
@@ -240,7 +239,7 @@ class Document(BaseDocument):
                     update_query["$unset"] = removals
                 if updates or removals:
                     last_error = collection.update(select_dict, update_query,
-                                                   upsert=upsert, **write_concern)
+                                                   upsert=True, **write_concern)
                     created = is_new_object(last_error)
 
             cascade = (self._meta.get('cascade', True)

tests/document/instance.py

@@ -852,6 +852,14 @@ class InstanceTest(unittest.TestCase):
         self.assertEqual(person.name, None)
         self.assertEqual(person.age, None)
 
+    def test_inserts_if_you_set_the_pk(self):
+        p1 = self.Person(name='p1', id=bson.ObjectId()).save()
+        p2 = self.Person(name='p2')
+        p2.id = bson.ObjectId()
+        p2.save()
+
+        self.assertEqual(2, self.Person.objects.count())
+
     def test_can_save_if_not_included(self):
 
         class EmbeddedDoc(EmbeddedDocument):