[SOLVED] undefined method `rels` for #<Neo4j::Core::Node:xxxxxxxx>

undefined method `rels` for #<Neo4j::Core::Node:xxxxxxxx>

Recently I upgraded to Neo4j 3.1.3, Neo4j.rb 8.0.13, and Neo4j-core 7.1.2. Since then, rels method throws undefined method 'rels' for #<Neo4j::Core::Node:xxxxxxxx> error.

My query is, student.rels(dir: :outgoing, type: :enrolled_in).count

Along with rels method, create_rel method is not working as well. I've been reading the docs to see if these two methods have been deprecated from newer versions, but no luck so far.

Solution

You might want to read the upgrade guide before reading the rest of this answer.

The rels relationship was not added to the Neo4j::Core::Node objects which replaced the old Node objects in the old API. I believe we also had a rels method in ActiveNode.

If you are using ActiveNode, the replacement is to define an association. Something like:

class Student
  include Neo4j::ActiveNode

  has_many :out, :all_nodes, type: :enrolled_in, model_class: false
end

# Then you can do:
student.all_nodes.count

However the fact that you're only following the enrolled_in relationship makes me think that this might be going to specific nodes (maybe Course?). If so I'd suggest doing:

class Course
  include Neo4j::ActiveNode
end

class
  include Neo4j::ActiveNode
  has_many :out, :courses, type: :enrolled_in 
  # model_class of `Course` will be assumed based on the association's name
end

If you aren't using ActiveNode but rather the neo4j-core gem directly, you should use a Cypher query