graphql-interface.rb

module Types::Interfaces::Node
  include Types::BaseInterface

  field :id, ID, null: false
end

module Types::Interfaces::Person
  include Types::BaseInterface

  field :first_name, String, null: false    
  field :last_name, String, null: true
end

module Types
  class CharacterType < BaseObject
    implements Types::Interfaces::Node
    implements Types::Interfaces::Person

    field :friends, [Types::CharacterType], null: true do 
      argument :last, Integer, required: false
    end
  end
end