add overlay support

ui/cli.py

@@ -45,6 +45,7 @@ class MDBase(object):
 		'modified': datetime.datetime.utcnow
 	}
 	_common_properties = [ 'type', 'created_by_ref' ] # XXX - add lang?
+	_common_optional = [ 'overlay_refs' ]
 	_common_names = set(_common_properties + _generated_properties.keys())
 
 	def __init__(self, obj):
@@ -64,7 +65,7 @@ class MDBase(object):
 
 	@classmethod
 	def create_obj(cls, obj):
-		'''Using obj as a base, create an instead of MDBase of the
+		'''Using obj as a base, create an instance of MDBase of the
 		correct type.
 
 		If the correct type is not found, a ValueError is raised.'''
@@ -422,6 +423,41 @@ class _TestCases(unittest.TestCase):
 		    self.created_by_ref)
 		self.assertEqual(oldid, files[0].id)
 
+	def test_mdbaseoverlay(self):
+		objst = ObjectStore(self.created_by_ref)
+
+		# that a base object
+		bid = uuid.uuid4()
+		objst.loadobj({
+			'type': 'metadata',
+			'uuid': bid,
+			'modified': datetime.datetime(2019, 6, 10, 14, 3, 10),
+			'created_by_ref': self.created_by_ref,
+			'hashes': [ 'sha256:91751cee0a1ab8414400238a761411daa29643ab4b8243e9a91649e25be53ada' ],
+			'someprop': [ 'somevalue' ],
+			'lang': 'en',
+		})
+
+		# can have an overlay object
+		oid = uuid.uuid4()
+		dhash = 'sha256:a7c96262c21db9a06fd49e307d694fd95f624569f9b35bb3ffacd880440f9787'
+		objst.loadobj({
+			'type': 'metadata',
+			'uuid': oid,
+			'modified': datetime.datetime(2019, 6, 10, 18, 3, 10),
+			'created_by_ref': self.created_by_ref,
+			'hashes': [ dhash ],
+			'overlay_refs': [ bid ],
+			'lang': 'en',
+		})
+
+		# and that when you get it's properties
+		oobj = objst.by_id(oid)
+		oitems = oobj.items()
+
+		# that is has the overlays property
+		print `oitems`
+
 	def test_objectstore(self):
 		objst = ObjectStore.load(os.path.join('fixtures', 'sample.data.pasn1'))