subscription on comments

orm/comment.py

@@ -25,7 +25,7 @@ class Comment(Base):
 	updatedBy = Column(ForeignKey("user.id"), nullable=True, comment="Last Editor")
 	deletedAt = Column(DateTime, nullable=True, comment="Deleted at")
 	deletedBy = Column(ForeignKey("user.id"), nullable=True, comment="Deleted by")
-	shout: int = Column(ForeignKey("shout.slug"), nullable=False)
+	shout = Column(ForeignKey("shout.slug"), nullable=False)
 	replyTo: int = Column(ForeignKey("comment.id"), nullable=True, comment="comment ID")
 	ratings = relationship(CommentRating, foreign_keys=CommentRating.comment_id)
 

resolvers/comments.py

@@ -5,6 +5,42 @@ from auth.authenticate import login_required
 import asyncio
 from datetime import datetime
 
+class CommentResult:
+	def __init__(self, status, comment):
+		self.status = status
+		self.comment = comment
+
+class CommentSubscription:
+	queue = asyncio.Queue()
+
+	def __init__(self, shout_slug):
+		self.shout_slug = shout_slug
+
+#TODO: one class for MessageSubscription and CommentSubscription
+class CommentSubscriptions:
+	lock = asyncio.Lock()
+	subscriptions = []
+
+	@staticmethod
+	async def register_subscription(subs):
+		self = CommentSubscriptions
+		async with self.lock:
+			self.subscriptions.append(subs)
+	
+	@staticmethod
+	async def del_subscription(subs):
+		self = CommentSubscriptions
+		async with self.lock:
+			self.subscriptions.remove(subs)
+	
+	@staticmethod
+	async def put(comment_result):
+		self = CommentSubscriptions
+		async with self.lock:
+			for subs in self.subscriptions:
+				if comment_result.comment.shout == subs.shout_slug:
+					subs.queue.put_nowait(comment_result)
+
 @mutation.field("createComment")
 @login_required
 async def create_comment(_, info, body, shout, replyTo = None):
@@ -18,6 +54,9 @@ async def create_comment(_, info, body, shout, replyTo = None):
 		replyTo = replyTo
 		)
 
+	result = CommentResult("NEW", comment)
+	await CommentSubscriptions.put(result)
+
 	return {"comment": comment}
 
 @mutation.field("updateComment")
@@ -38,6 +77,11 @@ async def update_comment(_, info, id, body):
 		
 		session.commit()
 
+	result = CommentResult("UPDATED", comment)
+	await CommentSubscriptions.put(result)
+
+	return {"comment": comment}
+
 @mutation.field("deleteComment")
 @login_required
 async def delete_comment(_, info, id):
@@ -54,6 +98,9 @@ async def delete_comment(_, info, id):
 		comment.deletedAt = datetime.now()
 		session.commit()
 
+	result = CommentResult("DELETED", comment)
+	await CommentSubscriptions.put(result)
+
 	return {}
 
 @mutation.field("rateComment")
@@ -63,16 +110,38 @@ async def rate_comment(_, info, id, value):
 	user_id = auth.user_id
 	
 	with local_session() as session:
+		comment = session.query(Comment).filter(Comment.id == id).first()
+		if not comment:
+			return {"error": "invalid comment id"}
+
 		rating = session.query(CommentRating).\
 			filter(CommentRating.comment_id == id and CommentRating.createdBy == user_id).first()
 		if rating:
 			rating.value = value
 			session.commit()
-			return {}
 	
+	if not rating:
 		CommentRating.create(
 			comment_id = id,
 			createdBy = user_id,
 			value = value)
 
+	result = CommentResult("UPDATED_RATING", comment)
+	await CommentSubscriptions.put(result)
+
 	return {}
+
+@subscription.source("commentUpdated")
+async def comment_generator(obj, info, shout):
+	try:
+		subs = CommentSubscription(shout)
+		await CommentSubscriptions.register_subscription(subs)
+		while True:
+			result = await subs.queue.get()
+			yield result
+	finally:
+		await CommentSubscriptions.del_subscription(subs)
+
+@subscription.field("commentUpdated")
+def comment_resolver(result, info, shout):
+	return result

schema.graphql

@@ -95,6 +95,19 @@ type TopicResult {
 	topic: Topic
 }
 
+enum CommentStatus {
+	NEW
+	UPDATED
+	UPDATED_RATING
+	DELETED
+}
+
+type CommentUpdatedResult {
+	error: String
+	status: CommentStatus
+	comment: Comment
+}
+
 ################################### Mutation
 
 type Mutation {
@@ -192,6 +205,7 @@ type Subscription {
 	shoutUpdated: Shout!
 	userUpdated: User!
 	topicUpdated(user_id: Int!): Shout!
+	commentUpdated(shout: String!): CommentUpdatedResult!
 }
 
 ############################################ Entities