This is an example GraphQL service written in Ruby, using Ruby on Rails and the graphql ruby gem.
This was built to accompany a talk at the LRUG August 2017 meeting. The slides for which can be found here:
https://speakerdeck.com/dazoakley/graphql-and-ruby
bundle install
bundle exec rails db:setup
bundle exec rails server
Now head to http://localhost:3000/graphiql to interact with the service.