Attribute not Backed by Database not Updating

Question

I'm trying to create a User model for my Ruby on Rails app that has a password field that is not saved in the database, but for some reason, it's not being updated correctly.

class User < ActiveRecord::Base
  attr :password
  validates_presence_of :email, :password_digest

  def password!
    password_digest = Digest::SHA1.hexdigest(password)
  end

  def password?(password)
    password_digest == Digest::SHA1.hexdigest(password)
  end
end

I'm using a very basic form to update the email and password.

= form_for @user do |f|
  -if @user.errors.any?
    #error_explanation
      %h2= "#{pluralize(@user.errors.count, "error")} prohibited this user from being saved:"
      %ul
        - @user.errors.full_messages.each do |msg|
          %li= msg

  .field
    = f.label :email
    = f.email_field :email, :required => true
  .field
    = f.label :password
    = f.password_field :password, :required => true
  .actions
    = f.submit 'Save'

In my controller I'm trying to use the basic update mechanism, though I am willing to add more code if I absolutely have to.

class UsersController < ApplicationController
  def create
    @user = User.new(params[:user])

    @user.password!

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

When this update is processed it throws a TypeError with the message: can't convert nil into String.

I've tried a few different ways to fix this, including manually setting the password using params[:user][:password] but it won't work. Can anyone spot the bug I'm missing?

Answer 1

In your password! method, you need to specify that you want to access the instance variable password_digest. Change to:

def password!
  self.password_digest = Digest::SHA1.hexdigest(password)
end