Ruby - CGI Sessions


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A CGI::Session maintains a persistent state for Web users in a CGI environment. Sessions should be closed after use, as this ensures that their data is written out to the store. When you've permanently finished with a session, you should delete it.

#!/usr/bin/ruby

require 'cgi'
require 'cgi/session'
cgi = CGI.new("html4")

sess = CGI::Session.new( cgi, "session_key" => "a_test", "prefix" => "rubysess.")
lastaccess = sess["lastaccess"].to_s
sess["lastaccess"] = Time.now
if cgi['bgcolor'][0] =~ /[a-z]/
   sess["bgcolor"] = cgi['bgcolor']
end

cgi.out{
   cgi.html {
      cgi.body ("bgcolor" => sess["bgcolor"]){
         "The background of this page"    +
         "changes based on the 'bgcolor'" +
         "each user has in session."      +
         "Last access time: #{lastaccess}"
      }
   }
}

Accessing "/cgi-bin/test.cgi?bgcolor = red" would turn the page red for a single user for each successive hit until a new "bgcolor" was specified via the URL.

Session data is stored in a temporary file for each session, and the prefix parameter assigns a string to be prepended to the filename, making your sessions easy to identify on the filesystem of the server.

CGI::Session still lacks many features, such as the capability to store objects other than Strings, session storage across multiple servers.

Class CGI::Session

A CGI::Session maintains a persistent state for web users in a CGI environment. Sessions may be memory-resident or may be stored on disk.

Class Methods

Ruby class Class CGI::Session provides a single class method to create a session −

CGI::Session::new( cgi[, option])

Starts a new CGI session and returns the corresponding CGI::Session object. option may be an option hash specifying one or more of the following −

  • session_key − Key name holding the session ID. Default is _session_id.

  • session_id − Unique session ID. Generated automatically

  • new_session − If true, create a new session id for this session. If false, use an existing session identified by session_id. If omitted, use an existing session if available, otherwise create a new one.

  • database_manager − Class to use to save sessions; may be CGI::Session::FileStore or CGI::Session::MemoryStore. Default is FileStore.

  • tmpdir − For FileStore, directory for session files.

  • prefix − For FileStore, prefix of session filenames.

Instance Methods

Sr.No. Methods & Description
1 [ ]

Returns the value for the given key. See example above.

2 [ ]=

Sets the value for the given key. See example above.

3 delete

Calls the delete method of the underlying database manager. For FileStore, deletes the physical file containing the session. For MemoryStore, removes the session from memory.

4 update

Calls the update method of the underlying database manager. For FileStore, writes the session data out to disk. Has no effect with MemoryStore.


ruby_web_applications.htm

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