## user_controller.rb
class UserController < ApplicationController
  before_filter :authorize, :except => :login

  layout "frontend" # => Show the stylesheet for the user side
  def login
    User.new
    if session[:user_id].nil?
      if request.get?
        # => If no session exists, create it
        @user = User.new
      else
        # => Create an instance of the model using the form data
        @user = User.new(params[:user])

        # => If either the username or password from the form don't exist, tell the user
        if (@user.name.empty? || @user.password.empty?)
          flash[:notice] = "Please input username <strong>and</strong> password"
        end

        # => Check if the username exists
        if is_user?(@user.name)
          # => Username exists, match the password to the user.
          if is_password?(@user.name, @user.password)
            flash[:notice] = "Password Matched"
          else
            flash[:notice] = "Password Incorrect"
          end
        else
          # => Username doesn't exist. Notify the user.
          flash[:notice] = "Username doesn't exist. Please try again."
        end

        # => Remember data if it user chose to do so
      end
    end
  end
end

## User.rb
require "digest/sha1"
class User < ActiveRecord::Base
  # User Levels
  # => 0  = Not loggedin
  # => 1  = Normal USer
  # => 90 = Admin
  # => 99 = Super Admin

  attr_accessor :password
  attr_accessible :name, :password, :userlevel, :message => 'is needed'
  validates_uniqueness_of :name
  validates_presence_of :name, :password
  validates_length_of :password, :in => 6..15

  def before_save
  # => Before save or update
    self.password = self.hash_password(self.password || "")
  end

  def after_save
  # => After save or update
    @password = nil
  end

  def is_user?(username)
  # => If the user is found, return TRUE, else FALSE
    return !User.find_by_name(username).nil?
  end

  def is_password?(username, password)
   self.find( :first,
         :conditions => ["name = ? and password = ?",
                         username, hash_password(password)])
  end

  def hash_password(password)
    return Digest::SHA1.hexdigest(password) # => SHA1 the password
  end
end

## Error
NoMethodError in UserController#login

undefined method `is_user?' for #<UserController:0x225a7d0>
RAILS_ROOT: /Users/zachinglis/Sites/rails/heroestheories/public/../config/..

Application Trace | Framework Trace | Full Trace
#{RAILS_ROOT}/app/controllers/user_controller.rb:21:in `login'