Neo4j.rb Unique Relationships

gistfile1.rb

class Novel < Neo4j::Rails::Model
  property :title, type: String, index: :exact

  has_n(:authored_by).to(Author)

end

class Author < Neo4j::Rails::Model
  property :name, type: String, index: :exact

  has_n(:authored).from(Novel.authored_by)
end

dune = Novel.find(title: 'Dune')
frank = Author.find(name: 'Frank Herbert')

# create basic relationship (this works great)
dune.authored_by
#=> Node dir: outgoing, Storage 9456 node: 14 rel_type: Novel#authored_by outgoing 0/ incoming 0/
dune.authored_by.count
#=> 0
dune.authored_by << frank
#=> Node dir: outgoing, Storage 9456 node: 14 rel_type: Novel#authored_by outgoing 1/ incoming 0/
dune.save
#=> true
dune.authored_by.count
#=> 1

# create it again... (works great....)
dune.authored_by << frank
#=> Node dir: outgoing, Storage 9462 node: 14 rel_type: Novel#authored_by outgoing 1/ incoming 0/
dune.save
#=> true
dune.authored_by.count
#=> 2

# but that's not really right. an author can only write a novel once.
# i really wanted unique relationships between two nodes.
# i know cypher can do this with CREATE UNIQUE.

# clean this up
dune.authored_by_rels.destroy_all
#=> nil

# i had to do some digging through the docs, and then the specs, but
# i found something that looked promising. `create_unique_path`.
Neo4j::Cypher.query(dune, frank){|novel, author| novel.create_unique_path(author){|n,a| n > rel(:authored_by).as(:link) > a }; ret(:link) }
#=> "START v1=node(14),v2=node(15) WITH v1,v2 CREATE UNIQUE (v1)-[link:`authored_by`]->(v2) RETURN link"

# oh hey, that looks great. let's execute this query!
Neo4j.query(dune, frank){|novel, author| novel.create_unique_path(author){|n,a| n > rel(:authored_by).as(:link) > a }; ret(:link) }
#=> NoMethodError: undefined method `createRelationshipTo' for #<Novel:0x19c50523>

# oh no! what happened? everything was going great. the raw query looked good.
# *shutdown rails console*
# *fireup Neo4j Admin web console*
# *execute that query by hand*
# *creates link!*