Andreas Ronge has written the Ruby bindings in JRuby, which utilizes the neo4j Java library underneath it. It can be embedded into an existing Rails application very easily.

This project can be accessed at https://github.com/neo4jrb/neo4j-core.

This project comes with an excellent documentation on how to use it with the Rail application.

Install gem neo4j-core on the machine, using the gem install neo4j-core command.

The complete documentation has been provided at https://github.com/neo4jrb/neo4j-core/wiki.

One sample example of creating nodes and relationships is shown as follows:

node = Neo4j::Node.create({name: 'neo'}, :hero, :human)
puts "Created node #{node[:name]} with labels #{node.labels.join(', ')}"

n1 = Neo4j::Node.create
n2 = Neo4j::Node.create
rel = n1.create_rel(:knows, n2, since: 2015)