A Ruby on Rails plugin that puts a countdown timer on the session object
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README.rdoc

session_countdown

A Ruby on Rails plugin that puts a countdown timer on the session object.

session.countdown_start(1.hour)
session.countdown_count #=> 3600
session.countdown_running? # => true
# 60 minutes pass
session.countdown_count #=> 0
session.countdown_running? # => false
session.countdown_expired? # => true
session.countdown_restart
session.countdown_running? # => true
session.countdown_abort
session.countdown_running? # => false
session.countdown_expired? # => false

But why?!?

Sometimes I need to build my own custom rails authentication systems rather than use plugins such as Authlogic, Devise or restful_authentication.

There is always a “timer” in my custom authentication contraptions, and there is always a session object lurking when I'm dealing with authentication stuff, so why not combine the two?

API

Note that countdown_abort(), countdown_restart() and countdown_count() will throw a NoCountdown exception if called on a non-existent countdown timer.

Start a countdown timer

session.countdown_start(seconds, name = :default)

You can have multiple countdown timers if you name them. The default countdown timer is named “default”.

Check if a countdown timer exists and is currently running

session.countdown_running?(name = :default)

Expire early (i.e. logout)

session.countdown_abort(name = :default)

Restart, using the duration supplied to countdown_start

session.countdown_restart(name = :default)

Check if expired

session.countdown_expired?(name = :default)

Remaining time in seconds

session.countdown_count(name = :default)

Understanding timer running, expired, and never started

countdown_running? == true # timer running
countdown_expired? == true # timer expired
countdown_running? == false && countdown_expired? == false # never ran

Synopsis

In application_controller.rb

before_filter :authorize

def authorize
  if session.countdown_running?
    session.countdown_restart # extend user's login
  else
    # store attempted access before rudely redirected to login screen
    session[:original_uri] = request.request_uri # rails3 use request.fullpath
    if session.countdown_expired?
      flash[:notice] = "Login Expired"
    else
      flash[:notice] = "Please login"
    end
    redirect_to :login
  end
end

In any controller

def login
  user = User.find_by_email(params[:email)
  if user && user.password_matches?(params[:password])
    session.countdown_start(1.hour)
    redirect_to :controller => :private
  else
    flash.now[:notice] = "Sorry, email/password wrong"
    render :index
  end

end

def logout
  session.countdown_abort
  flash[:notice] = "You are now logged out"
  redirect_to :index
end

In user model

def before_save
  if self.password_changed?
    self.salt = SecureRandom.hex(10)
    self.password = Digest::MD5.hexdigest(self.salt + self.password)
  end
end

def password_matches?(password_to_match)
  self.password == Digest::MD5.hexdigest(self.salt + password_to_match)
end

Note: Remember me

If you want an “remember me” feature you need to do two things.

Set timer for far future when user checks “remember me”

session.countdown_start(1.year)

Tell rails to serve up a persistent cookie instead of session cookie, probably in application_controller.rb

ActionController::Base.session_options[:expire_after] = 1.year

Persistent vs session cookies

There are two types of browser cookies: ones with expiration dates and ones without. When a cookie doesnt have an expiration date it's a session cookie and will be deleted when the browser quits. If the cookie has an expiration date it's a persistent cookie (a.k.a. domain cookie) and will be valid until that date.

“Remember me” could work fine with only session cookies, provided the user never quits the browser, but users expect “remember me” to never expire their login and to persist across browser quits. It also makes sense to set a far future expiration date or the cookie will eventually expire before the login does.