在Rails API应用程序中使用版本控制 - 无法为特定控制器操作呈现JSON

Question

我创建了一个练习rails应用程序，其中创建了名称空间并版本化，如在此railscast中演示的那样。一切工作正常，我可以看到在

然后，我添加了Rabl的宝石浏览器的JSON输出，并试图使Rabl的意见，但我得到浏览器中呈现一个空的JSON数组

这里是什么我系统地进行了版本控制工作

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: "{}" 

很明显，它无法访问实例变量。似乎是超出范围的一些问题。我不知道如何继续下一步。我找不到任何与rabl版本相关的例子。有什么建议么？我真的很感激它

谢谢

Answer 1

你在哪里设置实例变量？首先，你可能应该在你的Api :: ApplicationController（或者类似的东西，基本上是Api模块中的每个其他控制器继承的控制器）中都有这样一行：respond_to :json。

你不需要这些：render 'api/v1/index.json.rabl'。

只需设置你的实例变量：

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

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