CODEWITHSUNDEEP
ruby-on-railsneo4j
L.D
L.D

Reputation: 1329

Neo4j query in neo4j-sh returns the right number of rows while query_as in RoR returns double the number of rows

Here are my classes, I am following the example provided at: https://github.com/neo4jrb/neo4j/tree/master/example/blog The application so far works for CRUD operations. Here are my model classes:

class Post
  include Neo4j::ActiveNode
  property :title
  property :description
  validates :title, presence: true
  index :title
  has_many :out, :comments, rel_class: PostComment
end

class Comment
  include Neo4j::ActiveNode
  property :body
  index :body
  has_one :in, :post, rel_class: PostComment
end

class PostComment
  include Neo4j::ActiveRel
  from_class Post
  to_class Comment
  type 'has_comments'
  property :created_at
end

I have 2 Posts. Post 1 has 3 Comments and Post 2 has one Comment. For comments in total. When I a run this query from the neo4j-shell I am getting the right number of records.

neo4j-sh (?)$ start n=node(*) match n-[:has_comments]->(m) return n,m;
4 rows
30 ms

This is correct. Now trying something similar form RoR I am getting 8 rows instead of 4.

2.1.5 :012 >   result = Post.query_as(:post).match("posts-[:has_comments]->(comment:Comment)").pluck(:post, :comment)
2.1.5 :014 > result.count
 => 8

Can't see what is wrong here. Any help will be much appreciated.

Upvotes: 1

Views: 98

Answers (1)

subvertallchris
subvertallchris

Reputation: 5482

I'd expect 6 rows, not 8, but maybe I'm overlooking something. Doesn't matter, really. Instead of returning post and comment independently, try returning post and collections of comment. You don't need query_as, either, you can do it purely through QueryProxy.

result = Post.as(:post).comments(:comment).pluck(:post, 'collect(comment)')
result.each do |pair|
  post = pair[0]
  comments_array = pair[1]
  comments_array.each do |comment|
    # do things
  end
end

We're going to have an includes method in soon that will automate most of this for you, you'll just be able to do Post.all.includes(:comments) and then post.comments.each won't result in an extra query.

Also note that the match you wrote in wrote in the shell isn't the same as what the gem is going to generate. Call to_cypher on your query prior to pluck to see what it's building. It own't include the return statement, so add that on: RETURN post, comment if you want to do it as is. The gem's Cypher is a little messy as of the latest release but it'll be cleaner in the next one.

Upvotes: 1

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