Rails self-join gives an error - ruby-on-rails

Question

I'm having troubles getting my friending model in Rails 4 working. I set up a friendship controller and modified my User model to use a self-join as follows.
Friendship Model:
class Friendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, class_name: "User", foreign_key: "friend_id"
validates_presence_of :user_id, :friend_id
end
User Model:
class User < ActiveRecord::Base
rolify
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :invitable, :database_authenticatable, :registerable, :confirmable,
:recoverable, :rememberable, :trackable, :validatable
has_many :items
has_many :friendships
end
My UserController:
class UsersController < ApplicationController
before_action :set_user, only: [:show, :edit, :update, :destroy]
before_filter :authenticate_user!
load_and_authorize_resource
def index
authorize! :index, #user, message: 'Not authorized as an administrator.'
#users = User.all
end
def update
authorize! :update, #user, message: 'Not authorized as an administrator.'
if #user.update_attributes(params[:user])
redirect_to users_path, notice: "User updated."
else
redirect_to users_path, alert: "Unable to update user."
end
end
def destroy
authorize! :destroy, #user, message: 'Not authorized as an administrator.'
user = User.find(params[:id])
unless user == current_user
user.destroy
redirect_to users_path, notice: "User deleted."
else
redirect_to users_path, notice: "Can't delete yourself."
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_user
#user = User.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def user_params
params.require(:user).permit( :name, :email, :role_ids, :id, :user_id )
end
end
The relevant portion of my log:
NoMethodError - undefined method friends' for nil:NilClass:
app/views/users/index.html.erb:32:in_app_views_users_index_html_erb__2019584293611114470_70229529361660'
Unless I've missed this completely, I should be able to access a friend as #users.friends but that gives me a NoMethod Error. I've also tried accessing it as #users.friendships but I get the same error.
I have run the migration and restarted my rails server. I don't know what I'm missing but I would sure appreciate a fresh set of eyes. I think it must be something with how I've set up the model.

Answer 1

The models look fine, however in the index method on UsersController you have the following line: #users = User.all. This creates an array of users which means you can't call .friends on it. You need to access each user individually through iteration
#users.each do |user|
user.friends
# ... more code
end
or some other means.