CGI::Session on mod_ruby

ruby-talk
1

The following script is a simple page counter that works well for me running
as an rhtml file on mod_ruby:

<%
require ‘cgi/session’

cgi = CGI.new(‘html4’)

session = CGI::Session.new(cgi)

session[‘count’] ||= 0
session[‘count’] = session[‘count’].to_i + 1

content must be output in this way in order for headers to be written:

cgi.out { "count: " + session[‘count’] }

session.close
%>

However, if I replace the line “cgi.out …” with "puts session[‘count’]"
the script fails incrediment indicating that a new session is being created
every time. I would assume this is because the right headers (cookies,
etc…) are not written out in the response. If you use CGI::Session are you
forced to use cgi.out rather than your own output method?

···

–
John Long
www.wiseheartdesign.com

2

from cgi/session.rb
…

Most session state is maintained on the server. However, a session

id must be passed backwards and forwards between client and server

to maintain a reference to this session state.

···

On Fri, 19 Dec 2003, John Long wrote:

Date: Fri, 19 Dec 2003 02:43:38 +0900
From: John Long ng@johnwlong.com
Newsgroups: comp.lang.ruby
Subject: CGI::Session on mod_ruby

The following script is a simple page counter that works well for me running
as an rhtml file on mod_ruby:

<%
require ‘cgi/session’

cgi = CGI.new(‘html4’)

session = CGI::Session.new(cgi)

session[‘count’] ||= 0
session[‘count’] = session[‘count’].to_i + 1

content must be output in this way in order for headers to be written:

cgi.out { "count: " + session[‘count’] }

session.close
%>

However, if I replace the line “cgi.out …” with “puts session[‘count’]”
the script fails incrediment indicating that a new session is being created
every time. I would assume this is because the right headers (cookies,
etc…) are not written out in the response. If you use CGI::Session are you
forced to use cgi.out rather than your own output method?

The simplest way to do this is via cookies. The CGI::Session class

provides transparent support for session id communication via cookies

if the client has cookies enabled.

If the client has cookies disabled, the session id must be included

as a parameter of all requests sent by the client to the server. The

CGI::Session class in conjunction with the CGI class will transparently

add the session id as a hidden input field to all forms generated

using the CGI#form() HTML generation method. No built-in support is

provided for other mechanisms, such as URL re-writing. The caller is

responsible for extracting the session id from the session_id

attribute and manually encoding it in URLs and adding it as a hidden

input to HTML forms created by other mechanisms. Also, session expiry

is not automatically handled.

…

that being said, you can always simply:

require ‘cgi’
require ‘cgi/session’
cgi = CGI.new
session = CGI::Session.new(cgi = CGI.new)
c = (session[‘count’] ||= 0)
printf “%s\ncount: %s\n”, cgi.header, c
session[‘count’] = session[‘count’].succ
session.close

this is all CGI#out really does anyhow.

-a

ATTN: please update your address books with address below!

===============================================================================

EMAIL :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
PHONE :: 303.497.6469
ADDRESS :: E/GC2 325 Broadway, Boulder, CO 80305-3328
STP :: Solar-Terrestrial Physics Data | NCEI
NGDC :: http://www.ngdc.noaa.gov/
NESDIS :: http://www.nesdis.noaa.gov/
NOAA :: http://www.noaa.gov/
US DOC :: http://www.commerce.gov/

The difference between art and science is that science is what we
understand well enough to explain to a computer.
Art is everything else.
– Donald Knuth, “Discover”

/bin/sh -c ‘for l in ruby perl;do $l -e “print "\x3a\x2d\x29\x0a"”;done’
===============================================================================