Display an Index of Admin Users in Ruby on Rails - ruby-on-rails

Question

I've completed the Michael Hartl Ruby on Rails Tutorial (for Rails 3) and I am wondering how you would go about displaying all the users that have been assigned the Admin attribute but on a separate page as it doesn't mention this anywhere.
users_controller.rb
class UsersController < ApplicationController
before_filter :authenticate, :only => [:index, :edit, :update, :destroy]
before_filter :correct_user, :only => [:edit, :update]
before_filter :admin_user, :only => :destroy
def show
#user = User.find(params[:id])
#microposts = #user.microposts.paginate(:page => params[:page])
#title = #user.name
end
def new
#user = User.new
#title = "Sign up"
end
def create
#user = User.new(params[:user])
if #user.save
sign_in #user
flash[:success] = "Welcome to University Sports!"
redirect_to #user
else
#title = "Sign up"
render 'new'
end
end
def edit
#title = "Edit user"
end
def update
#user = User.find(params[:id])
if #user.update_attributes(params[:user])
flash[:success] = "Profile updated."
redirect_to #user
else
#title = "Edit user"
render 'edit'
end
end
def index
#users = User.paginate(:page => params[:page])
end
def admins
#users = User.admins
render "users/index"
end
def destroy
User.find(params[:id]).destroy
flash[:success] = "User destroyed."
redirect_to users_path
end
def following
#title = "Following"
#user = User.find(params[:id])
#users = #user.following.paginate(:page => params[:page])
render 'show_follow'
end
def followers
#title = "Followers"
#user = User.find(params[:id])
#users = #user.followers.paginate(:page => params[:page])
render 'show_follow'
end
private
def authenticate
deny_access unless signed_in?
end
def correct_user
#user = User.find(params[:id])
redirect_to(root_path) unless current_user?(#user)
end
def admin_user
redirect_to(root_path) unless current_user.admin?
end
end
Routes.rb
FinalProject::Application.routes.draw do
get "club/new"
resources :users do
member do
get :following, :followers
end
end
resources :users do
collection do
get :admins
end
end
resources :sessions, :only => [:new, :create, :destroy]
resources :microposts, :only => [:create, :destroy]
resources :relationships, :only => [:create, :destroy]
get "sessions/new"
match '/signup', :to => 'users#new'
match '/signin', :to => 'sessions#new'
match '/signout', :to => 'sessions#destroy'
match '/sign_up', :to => 'pages#sign_up'
root :to => 'pages#home'
resources :users
match '/signup', :to => 'users#new'
end
user.rb
class User < ActiveRecord::Base
attr_accessor :password
attr_accessible :name, :email, :password, :password_confirmation
has_many :microposts, :dependent => :destroy
has_many :relationships, :foreign_key => "follower_id", :dependent => :destroy
has_many :following, :through => :relationships, :source => :followed
has_many :reverse_relationships, :foreign_key => "followed_id", :class_name => "Relationship", :dependent => :destroy
has_many :followers, :through => :reverse_relationships, :source => :follower
email_regex = /\A[\w+\-.]+#[a-z\d\-.]+\.[a-z]+\z/i
validates :name, :presence => true, :length => { :maximum => 50 }
validates :email, :presence => true, :format => { :with => email_regex }, :uniqueness => { :case_sensitive => false }
scope :admins, where(:admin => true)
# Automatically create the virtual attribute 'password_confirmation'.
validates :password, :presence => true, :confirmation => true, :length => { :within => 6..40 }
before_save :encrypt_password
def has_password?(submitted_password)
encrypted_password == encrypt(submitted_password)
end
def self.authenticate(email, submitted_password)
user = find_by_email(email)
return nil if user.nil?
return user if user.has_password?(submitted_password)
end
def self.authenticate_with_salt(id, cookie_salt)
user = find_by_id(id)
(user && user.salt == cookie_salt) ? user : nil
end
def following?(followed)
relationships.find_by_followed_id(followed)
end
def follow!(followed)
relationships.create!(:followed_id => followed.id)
end
def unfollow!(followed)
relationships.find_by_followed_id(followed).destroy
end
def feed
Micropost.from_users_followed_by(self)
end
private
def encrypt_password
self.salt = make_salt unless has_password?(password)
self.encrypted_password = encrypt(password)
end
def encrypt(string)
secure_hash("#{salt}--#{string}")
end
def make_salt
secure_hash("#{Time.now.utc}--#{password}")
end
def secure_hash(string)
Digest::SHA2.hexdigest(string)
end
end

Answer 1

First, you would need to create a route in your config/routes.rb file that would route to an action that would display this information. Something like this:
resources :users do
collection do
get :admins
end
end
That would route to the admins action inside the UsersController, and so that's what you'll need to define next. It would go like this:
def admins
#users = User.admins
render "users/index"
end
Because the list of admins shouldn't be too different from the users list, you can just assign all the admins to #users and then render the users/index template... if it exists. I'm probably assuming too much here, but it's one way of doing it.
Now, there's no admins method on your User class and so you'll need to define that. One way to do that is with a scope, like this:
scope :admins, where(:admin => true)
This will define the admins method on the User class, returning a scope of all users who are admins. Scopes are cool, you should look into what else they can do.
Alternatively, you can define a class method:
def self.admins
where(:admin => true)
end

Answer 2

You should do the following:
UsersController
def admins
#admins=User.where(:admin => true)
end
And add this to your routes file:
resources :users do
collection do
get :admins
end
end
And then just render the #admins instance variable in the admins.html.erb view (which youll have you create in the User views).