Rails Framework is web services ready and it comes with built-in web services functions and methods that makes it easy for the Rails developer to expose controller’s actions as JSON services. In order to create a service, you need to start with our traditional model.

rails generate resource Item name
rake db:migrate

Next step is to implement actual service interfaces by modifying app/controllers/item_controller.rb

class ItemsController < ApplicationController
 before_action :set_item, only: [:show, :edit, :update, :destroy]

 def  index
  @items = Item.all
  respond_to do |format|
   format.json {render json: @items}
  end
end
def update
 respond_to do |format|
 if @item.update(item_params)
  format.json {render :show, status: :ok, location: @item}
 end
end

 private //callbacks
 def item_params
  params.require(:item).permit(:name)
 end
 def set_item
  @item = Item.find(params[:id])
 end
end

As you can see form the example above, item_controller.rb is used to implement JSON CRUD operations for the items table. It is easy to draw parallels between JSON and HTML controllers if you compare two so there is little learning curve for implementing either one in Rails.

It is not too difficule to query Web Services that we created in our example. In order to do so, you need to include references to

gem “rest-client”
require “rest_client”
RestClient.get “http://localhost:3000/items”
{:params => {:id=1}, :accept=>:json}
RestClient.post “http://localhost:3000/items”
{“name”=>”test”}.to_json, :content_type=>:json, :accept=>:json}