Generalize the _make_list() function for objects

Each object with a list duplicated the _make_list() method in its
own module. This removes that duplication and adds a generalized
helper in objects/base.py. The instance object still uses its own
because it has to do a bunch of other stuff in the loop for
efficiency.

Change-Id: Ic910f39087ebc167b2b930979f7951116caf8598

nova/compute/cells_api.py

@@ -22,6 +22,7 @@ from nova.cells import utils as cells_utils
 from nova.compute import api as compute_api
 from nova.compute import rpcapi as compute_rpcapi
 from nova import exception
+from nova.objects import base as obj_base
 from nova.objects import service as service_obj
 from nova.openstack.common import excutils
 from nova import rpcclient
@@ -480,7 +481,7 @@ class HostAPI(compute_api.HostAPI):
         # NOTE(danms): Currently cells does not support objects as
         # return values, so just convert the db-formatted service objects
         # to new-world objects here
-        return service_obj._make_list(context,
+        return obj_base.obj_make_list(context,
                                       service_obj.ServiceList(),
                                       service_obj.Service,
                                       services)

nova/objects/aggregate.py

@@ -144,22 +144,15 @@ class Aggregate(base.NovaObject):
         return self.metadata.get('availability_zone', None)
 
 
-def _make_list(context, list_obj, item_cls, db_list):
-    list_obj.objects = []
-    for db_item in db_list:
-        item = item_cls._from_db_object(context, item_cls(), db_item)
-        list_obj.objects.append(item)
-    list_obj.obj_reset_changes()
-    return list_obj
-
-
 class AggregateList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_all(cls, context):
         db_aggregates = db.aggregate_get_all(context)
-        return _make_list(context, AggregateList(), Aggregate, db_aggregates)
+        return base.obj_make_list(context, AggregateList(), Aggregate,
+                                  db_aggregates)
 
     @base.remotable_classmethod
     def get_by_host(cls, context, host):
         db_aggregates = db.aggregate_get_by_host(context, host)
-        return _make_list(context, AggregateList(), Aggregate, db_aggregates)
+        return base.obj_make_list(context, AggregateList(), Aggregate,
+                                  db_aggregates)

nova/objects/base.py

@@ -528,3 +528,26 @@ def obj_to_primitive(obj):
         return result
     else:
         return obj
+
+
+def obj_make_list(context, list_obj, item_cls, db_list, **extra_args):
+    """Construct an object list from a list of primitives.
+
+    This calls item_cls._from_db_object() on each item of db_list, and
+    adds the resulting object to list_obj.
+
+    :param:context: Request contextr
+    :param:list_obj: An ObjectListBase object
+    :param:item_cls: The NovaObject class of the objects within the list
+    :param:db_list: The list of primitives to convert to objects
+    :param:extra_args: Extra arguments to pass to _from_db_object()
+    :returns: list_obj
+    """
+    list_obj.objects = []
+    for db_item in db_list:
+        item = item_cls._from_db_object(context, item_cls(), db_item,
+                                        **extra_args)
+        list_obj.objects.append(item)
+    list_obj._context = context
+    list_obj.obj_reset_changes()
+    return list_obj

nova/objects/compute_node.py

@@ -92,23 +92,16 @@ class ComputeNode(base.NovaObject):
         return self._cached_service
 
 
-def _make_list(context, list_obj, item_cls, db_list):
-    list_obj.objects = []
-    for db_item in db_list:
-        item = item_cls._from_db_object(context, item_cls(), db_item)
-        list_obj.objects.append(item)
-    list_obj.obj_reset_changes()
-    return list_obj
-
-
 class ComputeNodeList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_all(cls, context):
         db_computes = db.compute_node_get_all(context)
-        return _make_list(context, ComputeNodeList(), ComputeNode, db_computes)
+        return base.obj_make_list(context, ComputeNodeList(), ComputeNode,
+                                  db_computes)
 
     @base.remotable_classmethod
     def get_by_hypervisor(cls, context, hypervisor_match):
         db_computes = db.compute_node_search_by_hypervisor(context,
                                                            hypervisor_match)
-        return _make_list(context, ComputeNodeList(), ComputeNode, db_computes)
+        return base.obj_make_list(context, ComputeNodeList(), ComputeNode,
+                                  db_computes)

nova/objects/instance_action.py

@@ -77,20 +77,11 @@ class InstanceAction(base.NovaObject):
         self._from_db_object(context, self, db_action)
 
 
-def _make_list(context, list_obj, item_cls, db_list):
-    list_obj.objects = []
-    for db_item in db_list:
-        item = item_cls._from_db_object(context, item_cls(), db_item)
-        list_obj.objects.append(item)
-    list_obj.obj_reset_changes()
-    return list_obj
-
-
 class InstanceActionList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_by_instance_uuid(cls, context, instance_uuid):
         db_actions = db.actions_get(context, instance_uuid)
-        return _make_list(context, cls(), InstanceAction, db_actions)
+        return base.obj_make_list(context, cls(), InstanceAction, db_actions)
 
 
 class InstanceActionEvent(base.NovaObject):
@@ -168,4 +159,5 @@ class InstanceActionEventList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_by_action(cls, context, action_id):
         db_events = db.action_events_get(context, action_id)
-        return _make_list(context, cls(), InstanceActionEvent, db_events)
+        return base.obj_make_list(context, cls(), InstanceActionEvent,
+                                  db_events)

nova/objects/keypair.py

@@ -56,20 +56,11 @@ class KeyPair(base.NovaObject):
         db.key_pair_destroy(context, self.user_id, self.name)
 
 
-def _make_list(context, list_obj, item_cls, db_list):
-    list_obj.objects = []
-    for db_item in db_list:
-        item = item_cls._from_db_object(context, item_cls(), db_item)
-        list_obj.objects.append(item)
-    list_obj.obj_reset_changes()
-    return list_obj
-
-
 class KeyPairList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_by_user(cls, context, user_id):
         db_keypairs = db.key_pair_get_all_by_user(context, user_id)
-        return _make_list(context, KeyPairList(), KeyPair, db_keypairs)
+        return base.obj_make_list(context, KeyPairList(), KeyPair, db_keypairs)
 
     @base.remotable_classmethod
     def get_count_by_user(cls, context, user_id):

nova/objects/service.py

@@ -119,25 +119,16 @@ class Service(base.NovaObject):
         db.service_destroy(context, self.id)
 
 
-def _make_list(context, list_obj, item_cls, db_list):
-    list_obj.objects = []
-    for db_item in db_list:
-        item = item_cls._from_db_object(context, item_cls(), db_item)
-        list_obj.objects.append(item)
-    list_obj.obj_reset_changes()
-    return list_obj
-
-
 class ServiceList(base.ObjectListBase, base.NovaObject):
     @base.remotable_classmethod
     def get_by_topic(cls, context, topic):
         db_services = db.service_get_all_by_topic(context, topic)
-        return _make_list(context, ServiceList(), Service, db_services)
+        return base.obj_make_list(context, ServiceList(), Service, db_services)
 
     @base.remotable_classmethod
     def get_by_host(cls, context, host):
         db_services = db.service_get_all_by_host(context, host)
-        return _make_list(context, ServiceList(), Service, db_services)
+        return base.obj_make_list(context, ServiceList(), Service, db_services)
 
     @base.remotable_classmethod
     def get_all(cls, context, disabled=None, set_zones=False):
@@ -145,4 +136,4 @@ class ServiceList(base.ObjectListBase, base.NovaObject):
         if set_zones:
             db_services = availability_zones.set_availability_zones(
                 context, db_services)
-        return _make_list(context, ServiceList(), Service, db_services)
+        return base.obj_make_list(context, ServiceList(), Service, db_services)

nova/tests/objects/test_objects.py

@@ -33,6 +33,14 @@ class MyObj(base.NovaObject):
               'missing': str,
               }
 
+    @staticmethod
+    def _from_db_object(context, obj, db_obj):
+        self = MyObj()
+        self.foo = db_obj['foo']
+        self.bar = db_obj['bar']
+        self.missing = db_obj['missing']
+        return self
+
     def obj_load_attr(self, attrname):
         setattr(self, attrname, 'loaded!')
 
@@ -234,6 +242,21 @@ class TestUtils(test.TestCase):
         self.assertEqual([{'foo': 0}, {'foo': 1}],
                          base.obj_to_primitive(mylist))
 
+    def test_obj_make_list(self):
+        class MyList(base.ObjectListBase, base.NovaObject):
+            pass
+
+        db_objs = [{'foo': 1, 'bar': 'baz', 'missing': 'banana'},
+                   {'foo': 2, 'bar': 'bat', 'missing': 'apple'},
+                   ]
+        mylist = base.obj_make_list('ctxt', MyList(), MyObj, db_objs)
+        self.assertEqual(2, len(mylist))
+        self.assertEqual('ctxt', mylist._context)
+        for index, item in enumerate(mylist):
+            self.assertEqual(db_objs[index]['foo'], item.foo)
+            self.assertEqual(db_objs[index]['bar'], item.bar)
+            self.assertEqual(db_objs[index]['missing'], item.missing)
+
 
 class _BaseTestCase(test.TestCase):
     def setUp(self):