Circular dependency detected while autoloading con

问题:

First of all: I googled and used the search here and found answers to the same error but on different setups. Maybe I broke sth different ;)

Error:

RuntimeError at /admin/users
Circular dependency detected while autoloading constant Admin::UsersController

The structure is:

App => controllers => admin => users_controller.rb

Routes:

namespace :admin do
  resources :stuff
  resources :users
end

Users controller:

class UsersController < Admin::BaseController
  def new
    #code
  end

  def create
    #code
  end

  def index
    #code
  end

  private

  def user_params
   #code
  end
end

Admin base controller

class Admin::BaseController < ApplicationController
  layout 'admin'
  before_filter :require_login
end

Using: Rails 4.1.4, Ruby 2.1.2 What did I do wrong here?

Thanks for your help!

Edit:

development.rb

Rails.application.configure do
 config.cache_classes = false
 config.eager_load = false
 config.consider_all_requests_local       = true
 config.action_controller.perform_caching = false
 config.action_mailer.raise_delivery_errors = false
 config.active_support.deprecation = :log
 config.active_record.migration_error = :page_load
 config.assets.debug = true
 config.assets.raise_runtime_errors = true
end

回答1:

It looks like the primary issue may just be that you haven't namespaced your UsersController under the Admin namespace, here:

class UsersController < Admin::BaseController

Simple fix:

class Admin::UsersController < Admin::BaseController

However, I suggest that you also break out your namespaces out into distinct parts to save future headache. So instead of the above, do this:

# app/controllers/admin/users_controller.rb
module Admin
  class UsersController < Admin::BaseController
    # ...
  end
end

And do the same with all other namespaced controllers, such as:

# app/controllers/admin/base_controller.rb
module Admin
  class BaseController < ApplicationController
    # ...
  end
end

This way, as Rails is loading and autoloading and so forth it will always be sure to define the Admin module before attempting to load the classes under it. Sometimes you get unknown constant errors otherwise. The reasoning is a bit complex, but if you'd like to have a look check out this post.

UPDATE

On Rails Edge, there is now an official Guide on the topic of Auto Loading of Constants.