Rails:获取嵌套资源的父对象

I have a nested resource that belongs to many different models. For instance:

我有一个嵌套资源，属于许多不同的模型。例如:

resources :users do
  resources :histories, only: [:show]
end

resources :publications do
  resources :histories, only: [:show]
end

resources :events do
  resources :histories, only: [:show]
end

In the HistoriesController, I want to find the parent object, though I'm having trouble thinking of a dry way to handle this. At the moment, the best I can come up with is:

在历史控制器中，我想找到父对象，尽管我想不出一个干巴巴的方法来处理它。目前，我能想到的最好的办法是:

if params[:user_id].present?
  @parent = User.find(params[:user_id])
elsif params[:publication_id].present?
  @parent = Publication.find(params[:publication_id])
elsif . . . .

I've got literally dozens of models I have to branch through in this way, which seems sloppy. Is there a better (perhaps baked-in) approach that I'm not considering?

我有几十个模型，我必须以这种方式进行分支，这看起来很草率。有没有更好的(可能是烘烤的)方法是我没有考虑的?

3 个解决方案

#1

not really a solution but you can get away with

不是一个真正的解决方案，但你可以侥幸过关

parent_klasses = %w[user publication comment]
if klass = parent_klasses.detect { |pk| params[:"#{pk}_id"].present? }
  @parent = klass.camelize.constantize.find params[:"#{klass}_id"]
end

if you are using a convention between your parameter name and your models

如果在参数名和模型之间使用约定

#2

The way I am doing this is adding the parent model class name as a default param in the route.

我这样做的方式是在路径中添加父模型类名作为默认参数。

For the question example this should be something like:

这个问题的例子应该是这样的:

resources :users, model_name: 'User' do
  resources :histories, only: [:show]
end

resources :publications, model_name: 'Publication' do
  resources :histories, only: [:show]
end

resources :events, model_name: 'Event' do
  resources :histories, only: [:show]
end

This will add the model name in the params hash.

这将在params散列中添加模型名。

Then in the controller/action you can get your parent model like:

然后在控制器/动作中，您可以得到父模型，如:

params[:model_name].constantize # Gives you the model Class (eg. User)

and the foreign key like:

外键是:

params[:model_name].foreign_key # Gives you column name (eg. user_id)

So you can do something like:

你可以这样做:

parent_class = params[:model_name].constantize
parent_foreing_key = params[:model_name].foreign_key

parent_object = parent_class.find(params[parent_foreing_key])

#3

As an alternative to the accepted answer, you could use a dynamic route like this:

作为被接受的答案的替代，你可以使用这样的动态路线:

get ':item_controller/:item_id/histories/:id', to: 'histories#show'

This should then should allow you to access the parent class something like this in your histories_controller.rb

然后，这应该允许您访问类似这样的父类

parent_controller = params[:item_controller]
parent_class = parent_controller.singularize.camelize.constantize
@parent = parent_class.find(params[:item_id])

You may be able to add a constraint on item_controller in the routes as well if you need to.

如果需要，还可以在路由中为item_controller添加约束。

#1