如何在模型中调用控制器方法

Question

I have a user model which has association with groups. The relation is given below

class User < ActiveRecord:;Base
  has_many :groups
end
class Group < ActiveRecord::Base
  belongs_to :user
  scope :user_groups, lambda { where(arel_table(:user_id).eq(@current_user.id) }
end

class ApplicationController < ActionController::Base
  def current_user
    @current_user ||= User.find(session['entity.user']) if session['entity.user']
  end
end

I want to filter current_user groups in my select_tag in group index page.

How to achieve this?

Answer 1

You should not access to this data inside the model (it is violating the MVC). You would be better to pass it as an argument to the scope:

scope :user_groups, 
           lambda { |user| where(arel_table(:user_id).eq(user.try(:id) || user) }

And call it like this:

User.user_groups(@current_user) # or you can pass @current_user.id, still works

Note : You can pass either an id (Integer) or a User Object to the user_groups lambda.

Answer 2

Sometimes you might need to check the current_user in model. So in current user method set following:

 ActiveRecord::Base.current_user = @current_user

This will helps in checking current_user in any model you define in future.

Answer 3

Saving value as class variable will not help as these class variables are shared between requests, although in development mode is this deactivated (see config.cache_classes = true|false), so another request can rewrite your variable value to its own value before you will read the value in model. As already mentioned, it is against MVC.