Grape gem 取り敢えず

config.ru

# -*- coding: utf-8 -*-
 
require 'grape'
 
module Cat
  class API < Grape::API
    prefix :api
 
    resource :cats do
      get ":id" do
        {
          :id   => params[:id],
          :name => "猫#{params[:id]}",
          :cry  => "にゃーん",
        }
      end
    end
  end
end
 
run Cat::API

$ rackup > /dev/null &

$ curl http://0.0.0.0:9292/api/cats/1.json
{"id":"1","name":"猫1","cry":"にゃーん"}

$ curl http://0.0.0.0:9292/api/cats/1.xml
<?xml version="1.0" encoding="UTF-8"?>
<hash>
  <id>1</id>
  <name>猫1</name>
  <cry>にゃーん</cry>
</hash>

$ curl http://0.0.0.0:9292/api/cats/2.json
{"id":"2","name":"猫2","cry":"にゃーん"}