Update group subject when notification received

session.py

@@ -441,6 +441,24 @@ class Session(YowsupApp):
 		self.groups[room].addParticipants(group.getParticipants(), self.buddies, self.legacyName)
 		self.groups[room].sendParticipantsToSpectrum(self.legacyName)
 
+	# Called by superclass
+	def onSubjectChanged(self, room, subject, subjectOwner, timestamp):
+		self.logger.debug(
+			"onSubjectChange(rrom=%s, subject=%s, subjectOwner=%s, timestamp=%s)",
+			room, subject, subjectOwner, timestamp)
+		try:
+			group = self.groups[room]
+		except KeyError:
+			self.logger.error("Subject of non-existant group (%s) changed", group)
+		else:
+			group.subject = subject
+			group.subjectOwner = subjectOwner
+			if not group.joined:
+				# We have not joined group so we should not send subject
+				return
+		self.backend.handleSubject(self.user, room, subject, subjectOwner)
+		self.backend.handleRoomNicknameChanged(self.user, room, subject)
+
 	# Called by superclass
 	def onParticipantsRemovedFromGroup(self, room, participants):
 		self.logger.debug("Participants removed from group: %s, %s",

yowsupwrapper.py

@@ -546,12 +546,23 @@ class YowsupApp(object):
 		"""
 		pass
 
+	def onSubjectChanged(self, group, subject, subjectOwner, timestamp):
+		"""Called when someone changes the grousp subject
+
+		Args:
+			- group: (str) id of the group (e.g. 27831788123-144024456)
+			- subject: (str) the new subject
+			- subjectOwner: (str) the number of the  person who changed the subject
+			- timestamp: (str) time the subject was changed
+		"""
+		pass
+
 	def onContactStatusChanged(self, number, status):
 		"""Called when a contacts changes their status
 
 		Args:
-			number: (str) the number of the contact who changed their status
-			status: (str) the new status
+		   number: (str) the number of the contact who changed their status
+		   status: (str) the new status
 		"""
 		pass
 
@@ -694,6 +705,13 @@ class YowsupAppLayer(YowInterfaceLayer):
 					entity.getGroupId().split('@')[0],
 					entity.getParticipants().keys()
 			)
+		elif isinstance(entity, SubjectGroupsNotificationProtocolEntity):
+			self.caller.onSubjectChanged(
+					entity.getGroupId().split('@')[0],
+					entity.getSubject(),
+					entity.getSubjectOwner(full=False),
+					entity.getSubjectTimestamp()
+			)
 		elif isinstance(entity, StatusNotificationProtocolEntity):
 			self.caller.onContactStatusChanged(
 					entity._from.split('@')[0],