是否有一種乾淨的方法來查找嵌套控制器中對象的多態實例？

Question

我正在使用具有多態關係的模型嵌套控制器。我想知道是否有一個乾淨的方式來找到@holder。 CommentsController#set_holder中的代碼很難看，我在想如果rails爲這個問題提供幫助。

class Comment < ActiveRecord::Base 
    belongs_to :holder, polymorphic: true 
end 

class Product < ActiveRecord::Base 
    has_many :comments, as: :holder 
end 

class User < ActiveRecord::Base 
    has_many :comments, as: :holder 
end 

Dummy::Application.routes.draw do 
    resources :products do 
    resources :comments 
    end 

    resources :users do 
    resources :comments 
    end 
end 

class CommentsController < ApplicationController 
    before_action :set_holder, only: [:new, :create] 

    # code ... 

    def new 
    @comment = @holder.comments.build 
    end 

    # code ... 

    private 

    def set_holder 
    # params = {"controller"=>"comments", "action"=>"new", "user_id"=>"3"} 
    # or 
    # params = {"controller"=>"comments", "action"=>"new", "product_id"=>"3"} 
    # Is there a Rails way to set @holder? 

    type, type_id = params.find { |k,_| /_id$/ === k } 
    @holder = type.sub(/_id$/, '').classify.constantize.find(type_id) 
    end 
end 

Answer 1

你可以嘗試使用：

resource, id = request.path.split('/')[1, 2] 
@holder = resource.classify.constantize.find(id) 

此外，在路線，你可以把事情通過短：

resources :users, :products do 
    resources :comments 
end