Lossing session value

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!

When I am using "Location:" to redirect the page to its original state and to prevent re-sending the upload again.
I am losing the value stored in the session, I need this value to display to the user the name of the file just uploaded.
I cant understand why this happens? Why isn't the value in the session available once the Location gets called? Any suggestion why or a better why to do this?
Here is a code prototype that shows what I am trying to do:

#!/usr/bin/perl

use strict;
use warnings;

use CGI;
use HTML::Template;
use Time::Piece;
use CGI::Session;
use Data::Dumper;

my $date_ntime = localtime->strftime('%Y%m%d%H%M%S');

my $cgi = CGI->new();

# Create new session
my $session = new CGI::Session("driver:File", undef, {Directory => 'se
+sh'})  or die CGI::Session->errstr;;

my $tmpl = HTML::Template->new(filename => 'templates/mini.tmpl', die_
+on_bad_params => 0, associate => $session);

my $got_file_name = $cgi->param( 'doc_upload' ) || '';

# Store file name to use later.
$session->param("doc_uploaded", $got_file_name);
my $filename_uploaded = $session->param("doc_uploaded");

# This is the return from the redirect 'Location:'
my $conf_msg = $cgi->param( 'conf' ) || '';

process_request($got_file_name, $date_ntime) if $got_file_name ;

# To prevent re-entering data twice by refreshing page.
confirmation($conf_msg) if $conf_msg; 

print $cgi->header, $tmpl->output;
exit;

sub process_request {
    
 my ($file_name, $date_ntime ) = @_;
 return unless $file_name ;

 my $file_renamed .=$date_ntime.".txt";
 my ($ext) = $file_name =~ /((\.[^.\s]+)+)$/;
 
 if ($ext =~ m/\.txt|\.csv$/) {

   $cgi->upload( 'doc_upload' );
   my $tmp_file = $cgi->tmpFileName( $file_name );
   rename( $tmp_file, $file_renamed );
   chmod 0664, $file_renamed;

   print 'Location: https://myserver/mini.pl?conf=1', "\r\n\r\n";
         
 }else {
    
   $tmpl->param(
             ERROR => 1,
           );

 }
 
}

sub confirmation {

 my ($message) = @_;
 return unless $message;

 my $text = $session->param("doc_uploaded");
 #my $text = $session->param(-name=>'doc_uploaded');
 
 $tmpl->param(
          MSG_OK => 1,
          #FILE_NAME => $text,
          FILE_NAME => $filename_uploaded,
             ) if $message;
         
}
[download]

Here is the template file:


<!DOCTYPE html>
<html lang="en">
<head>
<title>Mini</title>
</head>
<body>
 <p><b>UP-load.</b></p>
 <form action="mini.pl" method="post" enctype="multipart/form-data">
  <input type="file" size="40" name="doc_upload">
  <input type="submit" name="doc_submit" value="Upload">
 </p>
 
</form>
  
<br>

<br>

 <TMPL_IF NAME="MSG_OK">
     
   <p>Transaction was successful!</p>
   <p>Filename: <TMPL_VAR NAME="FILE_NAME"></p>
      
 </TMPL_IF>
 
 <TMPL_IF NAME="MSG">
     
   <p>WARNING: file <TMPL_VAR NAME="FILE_NAME"> already exists.</p>
   <p>Check and try again.</p>
    
 </TMPL_IF>
 
 <TMPL_IF NAME="ERROR">

  <p>Wrong file type.</p>

 </TMPL_IF>

 
</body>
</html>
[download]

Thanks for looking!

Comment on Lossing session value Select or Download Code

Replies are listed 'Best First'.
Re: Losing session value by hippo (Bishop) on Dec 13, 2017 at 16:36 UTC
Why isn't the value in the session available once the Location gets called? Because you are over-writing it with an empty string here: `my $got_file_name = $cgi->param( 'doc_upload' ) \|\| ''; # Store file name to use later. $session->param("doc_uploaded", $got_file_name);` [download]	[reply] [d/l]
Re^2: Losing session value by Anonymous Monk on Dec 13, 2017 at 16:49 UTC
No, that didn't work! Even removing the check for empty value `my $got_file_name = $cgi->param( 'doc_upload' );` from the code I am still losing the session value.	[reply] [d/l]
Re^3: Losing session value by hippo (Bishop) on Dec 13, 2017 at 16:59 UTC
You are not checking for an empty value, you are setting one. And if you don't do that, you are setting it to `undef` which is just as bad. Here is what I think you should be doing: `my $got_file_name = $cgi->param( 'doc_upload' ); # Store file name to use later but only if it is defined. $session->param("doc_uploaded", $got_file_name) if $got_file_name; my $filename_uploaded = $session->param("doc_uploaded");` [download]	[reply] [d/l] [select]
Re^4: Losing session value by Anonymous Monk on Dec 13, 2017 at 17:34 UTC
Re^5: Losing session value by hippo (Bishop) on Dec 14, 2017 at 09:34 UTC
Re: Lossing session value by poj (Abbot) on Dec 13, 2017 at 19:01 UTC
Add in `$cgi` or you get a new session each time. Get the session id `# Create new session my $session = new CGI::Session("driver:File", $cgi, {Directory => 'ses +'}) or die CGI::Session->errstr;; my $sid = $session->id();` [download] Add the session parameter in here. Use `.=` to ensure a string and not a file handle. `my $got_file_name .= $cgi->param( 'doc_upload' ) \|\| $session->param( 'doc_uploaded' ) \|\| '';` [download] Write the session to disk with flush `# Store file name to use later. $session->param("doc_uploaded", $got_file_name); $session->flush;` [download] Store the session id in a cookie `my $cookie = $cgi->cookie(CGISESSID => $sid); print $cgi->header(-cookie=>$cookie ), $tmpl->output;` [download] Add sessionid to redirect `print "Location: https://myserver/mini.pl?conf=1;CGISESSID=$sid\r\n +\r\n";` [download] poj	[reply] [d/l] [select]
Re^2: Lossing session value by Anonymous Monk on Dec 13, 2017 at 19:30 UTC
I added this new code you suggested, plus the others: `print "Location: https://myserver/mini.pl?conf=1;CGISESSID=$sid\r\n\r\n";` Now I get this in my browser: "This page isn�t working redirected you too many times." And nothing gets displayed!	[reply] [d/l]
Re^3: Lossing session value by poj (Abbot) on Dec 13, 2017 at 20:03 UTC
I'm not exactly sure what you are trying to achieve but revise the logic like this `# To prevent re-entering data twice by refreshing page. if ($conf_msg){ confirmation($conf_msg) } else { process_request($got_file_name, $date_ntime); }` [download] poj	[reply] [d/l]
Re: Lossing session value (cgi101) by Anonymous Monk on Dec 14, 2017 at 02:18 UTC
Hi Did you skip all the documentation of CGI::Session? `# Send proper HTTP header with cookies: print $session->header();` [download]	[reply] [d/l]


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