Calculate 4 newest comments per post in query - neo4j

Question

I have the following query to get posts with calculated number of likes and calculated user who created the post:
MATCH (post:Post)
WITH post
ORDER BY post.createdAt DESC
MATCH (user:User)-[:CREATED]->(post)
RETURN post, user.username AS createdBy,
size((post)<-[:LIKES]-(:User)) AS likes
SKIP {skip}
LIMIT {limit}
What I need is to calculate last 4 created comments for every post. If there is 0 comments, I would like to have returned empty array and there is also possibility that post has less then 4 comments, so will just show array of these comments.
I need smth like this (I added imaginary query):
MATCH (post:Post)
WITH post
ORDER BY post.createdAt DESC
MATCH (user:User)-[:CREATED]->(post)
[MATCH (comment:Comment)-[:BELONGS_TO]->(post:Post) ORDER BY comment.timestamp ASC]
RETURN post, user.username AS createdBy,
size((post)<-[:LIKES]-(:User)) AS likes,
comment AS comments
SKIP {skip}
LIMIT {limit}

Answer 1

This might do what you want:
MATCH (user:User)-[:CREATED]->(post:Post)
WITH user, post
ORDER BY post.createdAt DESC
OPTIONAL MATCH (post)<-[:BELONGS_TO]-(comment:Comment)
WITH user, post, comment
ORDER BY comment.timestamp DESC
RETURN post, user.username AS createdBy,
size((post)<-[:LIKES]-(:User)) AS likes,
COLLECT(comment)[0..4] AS latestComments
SKIP {skip}
LIMIT {limit}
It returns the posts (in descending order), and for each post it returns the creator's name, the number of likes, and a collection of (up to) the last 4 comments. It uses OPTIONAL MATCH to ensure that it returns posts that have no comments at all.