From 08fb09e878dcaedbb446e18502a6172fa4d43121 Mon Sep 17 00:00:00 2001
From: Balazs Gibizer <balazs.gibizer@ericsson.com>
Date: Fri, 8 Jun 2018 17:57:07 +0200
Subject: [PATCH] Fix unbound local when saving an unchanged RequestSpec

RequestSpec._get_update_primitives() tried to return the unitialized
db_updates field when the object has no changes. This patch initalizes
that local to None and handles that None in create() and save() where
the RequestSpec._get_update_primitives() is called.

Change-Id: Iad256079945bf8b5745ebdcc393c55115dbcab75
Closes-Bug: #1775863
---
 nova/objects/request_spec.py                 | 13 +++++++++----
 nova/tests/unit/objects/test_request_spec.py | 10 ++++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/nova/objects/request_spec.py b/nova/objects/request_spec.py
index 5db3d26a89b7..2119f90bf205 100644
--- a/nova/objects/request_spec.py
+++ b/nova/objects/request_spec.py
@@ -513,6 +513,7 @@ class RequestSpec(base.NovaObject):
         it was originally scheduled with.
         """
         updates = self.obj_get_changes()
+        db_updates = None
         # NOTE(alaski): The db schema is the full serialized object in a
         # 'spec' column.  If anything has changed we rewrite the full thing.
         if updates:
@@ -538,7 +539,9 @@ class RequestSpec(base.NovaObject):
                                               reason='already created')
 
         updates = self._get_update_primitives()
-
+        if not updates:
+            raise exception.ObjectActionError(action='create',
+                                              reason='no fields are set')
         db_spec = self._create_in_db(self._context, updates)
         self._from_db_object(self._context, self, db_spec)
 
@@ -556,9 +559,11 @@ class RequestSpec(base.NovaObject):
     @base.remotable
     def save(self):
         updates = self._get_update_primitives()
-        db_spec = self._save_in_db(self._context, self.instance_uuid, updates)
-        self._from_db_object(self._context, self, db_spec)
-        self.obj_reset_changes()
+        if updates:
+            db_spec = self._save_in_db(self._context, self.instance_uuid,
+                                       updates)
+            self._from_db_object(self._context, self, db_spec)
+            self.obj_reset_changes()
 
     @staticmethod
     @db.api_context_manager.writer
diff --git a/nova/tests/unit/objects/test_request_spec.py b/nova/tests/unit/objects/test_request_spec.py
index 2ae92adbe03a..4649327cbb87 100644
--- a/nova/tests/unit/objects/test_request_spec.py
+++ b/nova/tests/unit/objects/test_request_spec.py
@@ -667,6 +667,16 @@ class _TestRequestSpecObject(object):
         primitive = destination.obj_to_primitive(target_version='1.0')
         self.assertNotIn('aggregates', primitive['nova_object.data'])
 
+    def test_create_raises_on_unchanged_object(self):
+        ctxt = context.RequestContext(uuids.user_id, uuids.project_id)
+        req_obj = request_spec.RequestSpec(context=ctxt)
+        self.assertRaises(exception.ObjectActionError, req_obj.create)
+
+    def test_save_can_be_called_on_unchanged_object(self):
+        req_obj = fake_request_spec.fake_spec_obj(remove_id=True)
+        req_obj.create()
+        req_obj.save()
+
 
 class TestRequestSpecObject(test_objects._LocalTest,
                             _TestRequestSpecObject):