letmein 
letmein is a minimalistic authentication plugin for Rails 3 applications. It doesn't have anything other than the UserSession (or WhateverSession) object that you can use to authenticate logins.
Setup
Plug the thing below into Gemfile and you know what to do after.
gem 'letmein'
If you want to authenticate User with database fields email, password_hash and password_salt you don't need to do anything. If you're authenticating something else, you want something like this in your initializers:
LetMeIn.configure do |conf|
conf.model = 'Account'
conf.attribute = 'username'
conf.password = 'password_crypt'
conf.salt = 'salty_salt'
end
When creating/updating a record you have access to password accessor.
>> user = User.new(:email => 'example@example.com', :password => 'letmein')
>> user.save!
=> true
>> user.password_hash
=> $2a$10$0MeSaaE3I7.0FQ5ZDcKPJeD1.FzqkcOZfEKNZ/DNN.w8xOwuFdBCm
>> user.password_salt
=> $2a$10$0MeSaaE3I7.0FQ5ZDcKPJe
Authentication
You authenticate using UserSession object. Example:
>> session = UserSession.new(:email => 'example@example.com', :password => 'letmein')
>> session.save
=> true
>> session.user
=> #<User id: 1, email: "example@example.com" ... >
When credentials are invalid:
>> session = UserSession.new(:email => 'example@example.com', :password => 'bad_password')
>> session.save
=> false
>> session.user
=> nil
Usage
There are no built-in routes/controllers/views/helpers or anything. I'm confident you can do those yourself, because you're awesome. But here's an example how you can implement the controller handling the login:
class SessionsController < ApplicationController
def create
@session = UserSession.new(params[:user_session])
@session.save!
# Store the user in session and get a fresh session id
session[:user_id] = @session.user.id
request.session_options[:renew] = true
flash[:notice] = "Welcome back #{@session.user.name}!"
redirect_to '/'
rescue LetMeIn::Error
flash.now[:error] = 'Invalid Credentials'
render :action => :new
end
end
Upon successful login you have access to session[:user_id]. The rest is up to you.
Authenticating Multiple Models
Yes, you can do that too. Let's assume you also want to authenticate admins that don't have email addresses, but have usernames.
LetMeIn.configure do |conf|
conf.models = ['User', 'Admin']
conf.attributes = ['email', 'username']
end
Bam! You're done. Now you have an AdminSession object that will use username and password to authenticate.
Overriding Session Authentication
By default user will be logged in if provided email and password match. If you need to add a bit more logic to that you'll need to create your own session object. In the following example we do an additional check to see if user is 'approved' before letting him in.
class MySession < LetMeIn::Session
# Model that is being authenticated is derived from the class name
# If you're authenticating multiple models you need to specify which one
@model = 'User'
def authenticate
super # need to authenticate with email/password first
unless user && user.is_approved?
# adding a validation error will prevent login
errors.add :base, "You are not approved yet, #{user.name}."
end
end
end
Copyright
(c) 2011 Oleg Khabarov, released under the MIT license