Change Object schema type to be array instead of string.

This is done so that nullable Object field's schema can be given the null or
object type property.

implements bp json-schema-for-versioned-object

Change-Id: I43b04a76cccc9d4f893162535050fed6940bee6c

oslo_versionedobjects/fields.py

@@ -838,7 +838,7 @@ class Object(FieldType):
             required_fields = [key for key, field in sorted(cls.fields.items())
                                if not field.nullable]
             schema = {
-                'type': 'object',
+                'type': ['object'],
                 'properties': {
                     namespace_key: {
                         'type': 'string'

oslo_versionedobjects/tests/test_fields.py

@@ -911,7 +911,7 @@ class TestObject(TestField):
         class TestFoo(TestFakeObject, obj_base.ComparableVersionedObject):
             fields = {
                 'name': fields.StringField(),
-                'bar': fields.ObjectField('TestBar')
+                'bar': fields.ObjectField('TestBar', nullable=True)
             }
 
         bar = TestBar(name='bar')
@@ -1041,7 +1041,7 @@ class TestObject(TestField):
                              'versioned_object.name',
                              'versioned_object.version',
                              'versioned_object.data'],
-                'type': 'object'
+                'type': ['object']
             },
             self.field.get_schema())
 

oslo_versionedobjects/tests/test_objects.py

@@ -2076,7 +2076,7 @@ class TestSchemaGeneration(test.TestCase):
     class FakeComplexObject(base.VersionedObject):
         fields = {
             'a_dict': fields.DictOfListOfStringsField(),
-            'an_obj': fields.ObjectField('FakeObject'),
+            'an_obj': fields.ObjectField('FakeObject', nullable=True),
             'list_of_objs': fields.ListOfObjectsField('FakeObject'),
         }
 
@@ -2085,7 +2085,7 @@ class TestSchemaGeneration(test.TestCase):
         self.assertEqual({
             '$schema': 'http://json-schema.org/draft-04/schema#',
             'title': 'FakeObject',
-            'type': 'object',
+            'type': ['object'],
             'properties': {
                 'versioned_object.namespace': {
                     'type': 'string'
@@ -2159,7 +2159,7 @@ class TestSchemaGeneration(test.TestCase):
                                              'versioned_object.name',
                                              'versioned_object.version',
                                              'versioned_object.data'],
-                                'type': 'object'},
+                                'type': ['object', 'null']},
                         'list_of_objs': {
                             'items': {
                                 'properties': {
@@ -2184,10 +2184,10 @@ class TestSchemaGeneration(test.TestCase):
                                              'versioned_object.name',
                                              'versioned_object.version',
                                              'versioned_object.data'],
-                                'type': 'object'},
+                                'type': ['object']},
                             'readonly': False,
                             'type': ['array']}},
-                    'required': ['a_dict', 'an_obj', 'list_of_objs'],
+                    'required': ['a_dict', 'list_of_objs'],
                     'type': 'object'},
                 'versioned_object.name': {'type': 'string'},
                 'versioned_object.namespace': {'type': 'string'},
@@ -2197,7 +2197,7 @@ class TestSchemaGeneration(test.TestCase):
                          'versioned_object.version',
                          'versioned_object.data'],
             'title': 'FakeComplexObject',
-            'type': 'object'}
+            'type': ['object']}
         self.assertEqual(expected_schema, schema)
 
         fake_obj = self.FakeComplexObject(