in reply to How to retrive value from session using Perl CGI.

Hi Ramesh.

I don't know where you got that code from, but it is some butt ugly code.

The good news is that if you want to get down with perl, there are much more elegant places to see code.

Have you seen the CGI::Session and CGI cpan pages?

I suggest you print them out and staple them together. Have them besides you when you code.

One tip: You have a lot of print statements thrown about here and there, this is mixing up feedback with logic. You should separate them. At one section of your code you should work out logic, what you are trying the computer to have do for you. There should be no 'result', feedback. Yet. You could store everything in a variable. .. 

#!/usr/bin/perl
# this code has not been tested/debugged
use Time::Format 'time_format';
use CGI;
use strict;
use warnings;

# logic part.. where you establish values solve problems
my $d = time_format('mm/dd/yy',time);
my $cgi = new CGI; 

# output part... better to separate 
# for your own organization's sake

my $html = 
 $cgi->header .
 $cgi->start_html .
 $cgi->h1('hello') .
 $cgi->p("Today is $d");

# now you print
print $html;
exit;

[download]

Which brings be to the other part... CGI can do a lot more then you think. And you should use that. Look up Ovid for more on that, and why.

It may seem like using those tools instead of just using print is overkill- it's not. In the long run you'll code faster and solve problems.

Replies are listed 'Best First'.
Re^2: How to retrive value from session using Perl CGI.
by ramesh_ps1 (Initiate) on Sep 12, 2007 at 10:02 UTC
    Hi, Thanks for the suggestion.

    I have modified the code based on your suggestion.
    Now my first page cookie1.cgi looks like this.


    #!/usr/bin/perl -w
    use CGI;
    use CGI::Session;
    use DBI;
    #my $sid = $q->cookie('SessionId') || $q->param('SessionId') || undef;
    my $db_name="db";
    my $db_host="dbhost";
    my $db_user="dbuser";
    my $db_pass="dbpass";
    # Prepare Database connection to store session values
    $dbh = DBI->connect("DBI:mysql:database=$db_name;
    host=$db_host","$db_user","$db_pass", {PrintError => 1, RaiseError => 1, AutoCommit => 1});

    my $q = new CGI;

    # Create new session vareable
    my $session = new CGI::Session("driver:MySQL;
    id:MD5", undef, {Handle=>$dbh});
    $session->param(-name =>'userid',-value => 'ramesh');

    $session->expire(5000);

    $cookie = $q->cookie(-name =>'SessionId',-value => $session->id );

    print $q->header(-cookie=>$cookie),
    $q->h3("Cookie contains : $cookie "),
    $q->start_html, $q->start_form(-name=>'testcookie',-method=>'post',-action=>'./cookie2.cgi'),
    $q->submit(-name=>'submit',-value=>'click to go to next page'),
    $q->end_form, $q->end_html;
    $dbh->disconnect();
    exit;


    I am able to store session ID in the cookie and retrive the same in the second page cookie2.cgi.
    Problem is, I am not able to retrive session data based on session ID obtained from cookie.
    I am trying to load session as follows,

    Session ID is obtained from cookie
    my $sid = $q->cookie('SessionId') || $q->param('SessionId') || undef;

    Load session and connect to mysql
    $session=CGI::Session->load("driver:MySQL;id:MD5", undef, {Handle=>$dbh});

    Assign session ID to session
    $session->param("id", $sid);

    Am I doing it correct?

    Please let me know how to access the session data of a specefic session based on the session ID stored in the cookie.

[reply]

      Ok, what I am going to show you may freak you out. But that's ok.

      This is not meant to overwhelm you. I hope this is more of an inspiration of what perl can really do for you

      What you are learning is very useful. I've gone through those motions like most of us here have. But also, you should have a hint of what's at the end of the rainbow..

      So.. here. I wrote this just for you. I'll come back later and explain a little more. This code is fully tested and functional. 

      package CGI::Application::Tutorial::Namegame;
use base 'CGI::Application';
use CGI::Application::Plugin::Session;
use CGI::Application::Plugin::Feedback ':all';
use CGI::Application::Plugin::AutoRunmode;
use CGI::Application::Plugin::Forward;
use strict;
use warnings;
use Carp;

sub setup {
   my $self = shift;
   $self->start_mode('choose_name');
}

sub choose_name : Runmode {
   my $self = shift;
   $self->_detect_name_change_request;

   my $q = $self->query;
   my $html = 
        $q->start_html
      . $self->_nav
      . $q->h1('Choose Name')
      . $q->start_form
      . $q->textfield('name')
      . $q->submit('save')
      . $q->end_form
      . $q->end_html;

   return $html;  
}


sub show_verse : Runmode {
   my $self = shift;   
   $self->_detect_name_change_request;

   my $name = $self->_get_name_chosen
      or return $self->forward('choose_name');   


   require Lingua::EN::Namegame;

   my $verse = Lingua::EN::Namegame::name2verse($name)
      or $self->feedback("Sorry, cannot generate verse for [$name]")
      and $self->session->clear('name')
      and return $self->forward('choose_name');
      
   my $q = $self->query;   
   my $html = 
        $q->start_html
      . $self->_nav
      . $q->h1('Your Verse:')
      . $q->pre($verse)
      . $q->end_html;

   return $html;   
}



sub _detect_name_change_request {
   my $self = shift;
     
   my $name = $self->query->param('name');
   defined $name or return 0;   

   $name=~/^\w+$/
      or $self->feedback('Your "name" input sucks.')
      and $self->feedback('Try again.')
      and return 0;

   $self->session->param( name => $name );
   $self->session->flush;
   $self->feedback("Ok, name choice saved for [$name].");
   return 1;
}



sub _get_name_chosen {
   my $self = shift;
   my $name = $self->session->param('name');
   defined $name
      or $self->feedback('no name chosen yet')
      and return;
      
   return $name;
}



sub _nav {
   my $self = shift;
   
   my $navetc = 
        $self->query->p(q{<a href="?rm=choose_name">Choose Name</a>})
      . $self->query->p(q{<a href="?rm=show_verse">Show Verse</a>})
      . $self->get_feedback_html;

   return $navetc;   
}

1;

      [download]

      here you can see what it does in action

[reply]
[d/l]

In Section Seekers of Perl Wisdom