Created: 2008-10-24 21:13
Updated: 2019-03-01 08:49
License: mit


An unobtrusive ruby authentication library based on ActiveRecord.

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Table of Contents

1. Introduction

1.a. Overview

Authlogic introduces a new type of model. You can have as many as you want, and name them whatever you want, just like your other models. In this example, we want to authenticate with our User model, which is inferred from the name:

class UserSession < Authlogic::Session::Base
  # specify configuration here, such as:
  # logout_on_timeout true
  # ...many more options in the documentation

In a UserSessionsController, login the user by using it just like your other models:

UserSession.create(:login => "bjohnson", :password => "my password", :remember_me => true)

session = => "bjohnson", :password => "my password", :remember_me => true)

# requires the authlogic-oid "add on" gem
UserSession.create(:openid_identifier => "identifier", :remember_me => true)

# skip authentication and log the user in directly, the true means "remember me"
UserSession.create(my_user_object, true)

The above handles the entire authentication process for you by:

  1. authenticating (i.e. validating the record)
  2. sets up the proper session values and cookies to persist the session (i.e. saving the record).

You can also log out (i.e. destroying the session):


After a session has been created, you can persist it (i.e. finding the record) across requests. Thus keeping the user logged in:

session = UserSession.find

To get all of the nice authentication functionality in your model just do this:

class User < ApplicationRecord
  acts_as_authentic do |c|
    c.my_config_option = my_value
  end # the configuration block is optional

This handles validations, etc. It is also "smart" in the sense that it if a login field is present it will use that to authenticate, if not it will look for an email field, etc. This is all configurable, but for 99% of cases that above is all you will need to do.

You may specify how passwords are cryptographically hashed (or encrypted) by setting the Authlogic::CryptoProvider option:

c.crypto_provider = Authlogic::CryptoProviders::BCrypt

Also, sessions are automatically maintained. You can switch this on and off with configuration, but the following will automatically log a user in after a successful registration:


You can switch this on and off with the following configuration:

class User < ApplicationRecord
  acts_as_authentic do |c|
    c.log_in_after_create = false
  end # the configuration block is optional

Authlogic also updates the session when the user changes his/her password. You can also switch this on and off with the following configuration:

class User < ApplicationRecord
  acts_as_authentic do |c|
    c.log_in_after_password_change = false
  end # the configuration block is optional

Authlogic is very flexible, it has a strong public API and a plethora of hooks to allow you to modify behavior and extend it. Check out the helpful links below to dig deeper.

1.b. Reference Documentation

This README is just an introduction, but we also have reference documentation.

To use the reference documentation, you must understand how Authlogic's code is organized. There are 2 models, your Authlogic model and your ActiveRecord model:

  1. Authlogic::Session, your session models that extend Authlogic::Session::Base.
  2. Authlogic::ActsAsAuthentic, which adds in functionality to your ActiveRecord model when you call acts_as_authentic.

2. Rails

Let's walk through a typical rails setup. (Compatibility)

2.a. The users table

If you want to enable all the features of Authlogic, a migration to create a User model might look like this:

class CreateUser < ActiveRecord::Migration
  def change
    create_table :users do |t|
      # Authlogic::ActsAsAuthentic::Email
      t.string    :email

      # Authlogic::ActsAsAuthentic::Password
      t.string    :crypted_password
      t.string    :password_salt

      # Authlogic::ActsAsAuthentic::PersistenceToken
      t.string    :persistence_token
      t.index     :persistence_token, unique: true

      # Authlogic::ActsAsAuthentic::SingleAccessToken
      t.string    :single_access_token
      t.index     :single_access_token, unique: true

      # Authlogic::ActsAsAuthentic::PerishableToken
      t.string    :perishable_token
      t.index     :perishable_token, unique: true

      # See "Magic Columns" in Authlogic::Session::Base
      t.integer   :login_count, default: 0, null: false
      t.integer   :failed_login_count, default: 0, null: false
      t.datetime  :last_request_at
      t.datetime  :current_login_at
      t.datetime  :last_login_at
      t.string    :current_login_ip
      t.string    :last_login_ip

      # See "Magic States" in Authlogic::Session::Base
      t.boolean   :active, default: false
      t.boolean   :approved, default: false
      t.boolean   :confirmed, default: false


In the User model,

class User < ApplicationRecord

  # Validate email, login, and password as you see fit.
  # Authlogic < 5 added these validation for you, making them a little awkward
  # to change. In 4.4.0, those automatic validations were deprecated. See
  validates :email,
    format: {
      with: /@/,
      message: "should look like an email address."
    length: { maximum: 100 },
    uniqueness: {
      case_sensitive: false,
      if: :will_save_change_to_email?

  validates :login,
    format: {
      with: /\A[a-z0-9]+\z/,
      message: "should use only letters and numbers."
    length: { within: 3..100 },
    uniqueness: {
      case_sensitive: false,
      if: :will_save_change_to_login?

  validates :password,
    confirmation: { if: :require_password? },
    length: {
      minimum: 8,
      if: :require_password?
  validates :password_confirmation,
    length: {
      minimum: 8,
      if: :require_password?

2.b. Controller

Your sessions controller will look just like your other controllers.

class UserSessionsController < ApplicationController
  def new
    @user_session =

  def create
    @user_session =
      redirect_to account_url
      render :action => :new

  def destroy
    redirect_to new_user_session_url


  def user_session_params
    params.require(:user_session).permit(:email, :password, :remember_me)

As you can see, this fits nicely into the conventional controller methods.

2.b.1. Helper Methods

class ApplicationController
  helper_method :current_user_session, :current_user

    def current_user_session
      return @current_user_session if defined?(@current_user_session)
      @current_user_session = UserSession.find

    def current_user
      return @current_user if defined?(@current_user)
      @current_user = current_user_session && current_user_session.user

2.c. View

<%= form_for @user_session do |f| %>
  <% if @user_session.errors.any? %>
  <div id="error_explanation">
    <h2><%= pluralize(@user_session.errors.count, "error") %> prohibited:</h2>
      <% @user_session.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
  <% end %>
  <%= f.label :login %><br />
  <%= f.text_field :login %><br />
  <br />
  <%= f.label :password %><br />
  <%= f.password_field :password %><br />
  <br />
  <%= f.submit "Login" %>
<% end %>

2.d. CSRF Protection

Because Authlogic introduces its own methods for storing user sessions, the CSRF (Cross Site Request Forgery) protection that is built into Rails will not work out of the box.

No generally applicable mitigation by the authlogic library is possible, because the instance variable you use to store a reference to the user session in def current_user_session will not be known to authlogic.

You will need to override ActionController::Base#handle_unverified_request to do something appropriate to how your app handles user sessions, e.g.:

class ApplicationController < ActionController::Base

  def handle_unverified_request
    # raise an exception
    fail ActionController::InvalidAuthenticityToken
    # or destroy session, redirect
    if current_user_session
    redirect_to root_url

3. Testing

See Authlogic::TestCase

4. Helpful links

5. Add-ons

If you create one of your own, please let us know about it so we can add it to this list. Or just fork the project, add your link, and send us a pull request.

6. Internals

Interested in how all of this all works? Think about an ActiveRecord model. A database connection must be established before you can use it. In the case of Authlogic, a controller connection must be established before you can use it. It uses that controller connection to modify cookies, the current session, login with HTTP basic, etc. It connects to the controller through a before filter that is automatically set in your controller which lets Authlogic know about the current controller object. Then Authlogic leverages that to do everything, it's a pretty simple design. Nothing crazy going on, Authlogic is just leveraging the tools your framework provides in the controller object.

90. Compatibility

Version branch ruby activerecord
5.0 master >= 2.3.0 >= 5.2, < 6.1
4.4 4-4-stable >= 2.3.0 >= 4.2, < 5.3
4.3 4-3-stable >= 2.3.0 >= 4.2, < 5.3
4.2 4-2-stable >= 2.2.0 >= 4.2, < 5.3
3 3-stable >= 1.9.3 >= 3.2, < 5.2
2 rails2 >= 1.9.3 ~> 2.3.0
1 ? ? ?

Under SemVer, changes to dependencies do not require a major release.

Intellectual Property

Copyright (c) 2012 Ben Johnson of Binary Logic, released under the MIT license

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