Rails Admin Controller

admin_controller.rb

class AdminController < ApplicationController
  layout 'admin'
end

routes.rb

  namespace :admin do
    resources :users
  end

users_controller.rb

module Admin
  class UsersController < AdminController

    # GET /users
    # GET /users.json
    def index
      @users = User.all

      respond_to do |format|
        format.html # index.html.erb
        format.json { render json: @users }
      end
    end

    # GET /users/1
    # GET /users/1.json
    def show
      @user = User.find(params[:id])

      respond_to do |format|
        format.html # show.html.erb
        format.json { render json: @user }
      end
    end

    # GET /users/new
    # GET /users/new.json
    def new
      @user = User.new

      respond_to do |format|
        format.html # new.html.erb
        format.json { render json: @user }
      end
    end

    # GET /users/1/edit
    def edit
      @user = User.find(params[:id])
    end

    # POST /users
    # POST /users.json
    def create
      @user = User.new(user_params)

      respond_to do |format|
        if @user.save
          format.html { redirect_to [:admin, @user], notice: 'User was successfully created.' }
          format.json { render json: @user, status: :created, location: [:admin, @user] }
        else
          format.html { render action: "new" }
          format.json { render json: @user.errors, status: :unprocessable_entity }
        end
      end
    end

    # PUT /users/1
    # PUT /users/1.json
    def update
      @user = User.find(params[:id])

      respond_to do |format|
        if @user.update_attributes(user_params)
          format.html { redirect_to [:admin, @user], notice: 'User was successfully updated.' }
          format.json { head :no_content }
        else
          format.html { render action: "edit" }
          format.json { render json: @user.errors, status: :unprocessable_entity }
        end
      end
    end

    # DELETE /users/1
    # DELETE /users/1.json
    def destroy
      @user = User.find(params[:id])
      @user.destroy

      respond_to do |format|
        format.html { redirect_to [:admin, :users] }
        format.json { head :no_content }
      end
    end

    private
      def user_params
        params.require(:user).permit(:email,
                                     :note,
                                     :password,
                                     :password_confirmation,
                                     :remember_me,
                                     :role)
      end
  end
end