Using versioning in a Rails API app- Cannot render JSON for a particular controller action

Question

I created a practice rails app where I have created a namespace and versioned like is demonstrated in this railscast . Everything is working fine and I can see the json output in the browser

Then I added the Rabl gem and was trying to render the rabl views but I get an empty JSON array rendered in the browser

Here is what I did systematically to get the versioning working

1) changed the routes file to look like this

App0828::Application.routes.draw do

 namespace :api, defaults: { format: 'json'} do
   namespace :v1 do
    resources :vendors
   end
 end

  #resources :vendors
  #root to: 'vendors#index'
end

2) The created thise files
    app/copntrollers/api/v1/vendors_controller.rb

  Inside the vendors_controller.rb I added the following code

 module Api
  module V1
  class VendorsController < ApplicationController

  class Vendor < ::Vendor
    #subclass vendor class so thatyou can extend its behaviour just for this version
    #add any functions specific to this version here
    end

  respond_to :json

  def index
    respond_with Vendor.all       
  end

  def show
    respond_with Vendor.find(params[:id])
  end
  ..........

3) Then I pointed my browser to this url "http://localhost:3000/api/v1/vendors"
   And I can see the json output in my browser

4) Then I added the rabl gem
5) restarted the server
6) Changed the above file at    app/copntrollers/api/v1/vendors_controller.rb
   from the version above to the version below

  module Api
   module V1
   class VendorsController < ApplicationController

    class Vendor < ::Vendor
      #subclass vendor class so thatyou can extend its behaviour just for this version
      #add any functions specific to this version here
    end

    respond_to :json

  def index
    render 'api/v1/index.json.rabl'
   end

  def show
    render 'api/v1/show.json.rabl'
  end

  .......
 7) I created the following files with this code:
     file: app/views/api/v1/show.json.rabl
     code:    object @vendor
              attributes :id, :name

     file: app/views/api/v1/index.json.rabl
     code:   object @vendors
             attributes :id, :name
 8) Routes file looks like this

 api_v1_vendors GET    /api/v1/vendors(.:format)   api/v1/vendors#index {:format=>"json"}

 POST   /api/v1/vendors(.:format)          api/v1/vendors#create {:format=>"json"}

 new_api_v1_vendor GET    /api/v1/vendors/new(.:format)      api/v1/vendors#new {:format=>"json"}

 edit_api_v1_vendor GET    /api/v1/vendors/:id/edit(.:format) api/v1/vendors#edit {:format=>"json"}

 api_v1_vendor GET    /api/v1/vendors/:id(.:format)      api/v1/vendors#show {:format=>"json"}
 PUT    /api/v1/vendors/:id(.:format)      api/v1/vendors#update {:format=>"json"}

 DELETE /api/v1/vendors/:id(.:format)      api/v1/vendors#destroy {:format=>"json"}

 9) Finally I went to url: "http://localhost:3000/api/v1/vendors.json"

  And all I see in the browser is an empty JSON hash: "{}"

So clearly it cannot access the instance variables. Seems to be some issue with being out of scope. Im not sure how to proceed next. I couldn't find any examples online of versioning with rabl. Any suggestions? Id really appreciate it

Thanks

Answer 1

Where are you setting the instance variables?

First, you probably should have this line: respond_to :json in your Api::ApplicationController (or something like that, basically the controller from which every other controller in the Api module inherit).

You dont need these: render 'api/v1/index.json.rabl' .

Just set your instance variables:

def index
    @vendors = Vendor.all
    respond_with @vendors
end

def show
    @vendor = Vendor.find(params[:id])
    respond_with @vendor
end