Rack Flash

flash[:notice] = "You can stop rolling your own now."

Simple flash hash implementation for Rack apps.

Try it out here: flash.patnakajima.net.

View the RDoc.

Usage

Here's how to use it.

Vanilla Rack apps

You can access flash entries via env['rack-flash']. You can treat it either like a regular flash hash:

env['rack-flash'][:notice] = 'You have logged out.'

Or you can pass the :accessorize option to declare your flash types. Each of these will have accessors defined on the flash object:

use Rack::Flash, :accessorize => [:notice, :error]

# Set a flash entry
env['rack-flash'].notice = 'You have logged out.'

# Get a flash entry
env['rack-flash'].notice # => 'You have logged out.'

# Set a a flash entry for only the current request
env['rack-flash'].notice! 'You have logged out.'

Sample rack app:

get = proc { |env|
  [200, {},
    env['rack-flash'].notice || 'No flash set. Try going to /set'
  ]
}

set = proc { |env|
  env['rack-flash'].notice = 'Hey, the flash was set!'
  [302, {'Location' => '/'},
    'You are being redirected.'
  ]
}

builder = Rack::Builder.new do
  use Rack::Session::Cookie
  use Rack::Flash, :accessorize => true

  map('/set') { run set }
  map('/')    { run get }
end

Rack::Handler::Mongrel.run builder, :Port => 9292

Sinatra

If you're using Sinatra, you can use the flash hash just like in Rails:

require 'sinatra/base'
require 'rack-flash'

class MyApp < Sinatra::Base
  use Rack::Flash

  post '/set-flash' do
    # Set a flash entry
    flash[:notice] = "Thanks for signing up!"
    
    # Get a flash entry
    flash[:notice] # => "Thanks for signing up!"
    
    # Set a flash entry for only the current request
    flash.now[:notice] = "Thanks for signing up!"
  end
end

If you've got any ideas on how to simplify access to the flash hash for vanilla Rack apps, let me know. It still feels a bit off to me.

Sweeping stale entries

By default Rack::Flash has slightly different behavior than Rails in that it doesn't delete entries until they are used. If you want entries to be cleared even if they are not ever accessed, you can use the :sweep option:

use Rack::Flash, :sweep => true

This will sweep stale flash entries, whether your not you actually use them.