Question

I’m trying to use redirects and sessions in Sinatra to pass some data around the site. Here’s a simplified example, using PrettyPrint for debugging:

require 'pp'

require 'rubygems'
require 'sinatra'

enable :sessions

get '/' do
  session[:foo] = '12345'

  puts 'session1'
  pp session

  redirect to('/redir')
end

get '/redir' do
  puts 'session2'
  pp session
  'hello world'
end

Looking at Thin’s output, I see:

>> Listening on 0.0.0.0:4567, CTRL+C to stop
session1
{"session_id"=>
  "ea587d8afdcb2ada64f9b17cdd1fbae7b192dee5dfc2999ff9d323f1528f6a0f",
 "foo"=>"12345"}
127.0.0.1 - - [19/Jul/2011 10:33:24] "GET / HTTP/1.1" 302 - 0.0042
session2
{}
127.0.0.1 - - [19/Jul/2011 10:33:24] "GET /redir HTTP/1.1" 200 11 0.0004

Everything I’ve seen in the docs suggests that this should work fine. In fact, I never get any session data for /redir, even if I request it directly, and the session persists as you’d expect on subsequent requests for /.

Thoughts?

Answer 1

It seems as though the session hash is not loaded until a session variable is referenced. So, for example, you get the expected result if you change the redirect handler to:

get '/redir' do
  puts 'session2'
  puts session[:foo]
  pp session
  'hello world'
end

I guess Sinatra is using the session directly from Rack. A quick peek at the source shows that the session hash is lazily loaded when the [] method (and others) are invoked:

https://github.com/rack/rack/blob/master/lib/rack/session/abstract/id.rb