Processing a multiple="multiple" <select>

jpk236 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I'm having some issues processing a Multiple Select box with Perl, and who else better to leverage than the Monks!

HTML:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http:/
+/www.w3.org/TR/2002/REC-xhtml1-20020801/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Test Form</title>
</head>
<body>
<form method="post" action="/cgi-bin/test_form.cgi">
Function:<br/>
<br/>
<select name="Blah[]" multiple="multiple">
<option value=""></option>
<option value="Blah1">Blah1</option> 
<option value="Blah2">Blah2</option> 
<option value="Blah3">Blah3</option> 
<option value="Blah4">Blah4</option> 
<option value="Blah5">Blah5</option> 
</select>
<br/><br/>
<input type="submit" value=" Submit " />
</form>
</body>
</html>
[download]

Perl:

#!/usr/bin/perl -w
use strict;

my ($buffer, $pair, $var, $payload, $i);
my (@pairs);
my (%POST);

read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});

@pairs = split(/&/, $buffer);

foreach $pair (@pairs) {
     ($var, $payload) = split(/=/, $pair);

     $payload =~ tr/+/ /;
     $payload =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;

     $POST{$var} = $payload;
}

foreach $i ($POST{Blah}) {
     print "Blah: ".$i."<br/>\n";
}
[download]

This is what I thought would work.

I've tried various ways of retrieving the data, and I either get nothing back or I only get back the last element.

Thanks for any help!

- Justin

Comment on Processing a multiple="multiple" <select> Select or Download Code

Replies are listed 'Best First'.
Re: Processing a multiple="multiple" <select> by Corion (Patriarch) on Sep 20, 2007 at 13:37 UTC
Don't do CGI decoding yourself, use CGI.pm or CGI::Lite: `#!/usr/bin/perl -w use strict; use CGI; my $q = CGI->new(); my @pairs = $q->param('Blah[]'); for (@pairs) { print "Blah: $_<br />\n"; };` [download] Update: It is `->param('Blah[]')`, not `->param('Blah')`	[reply] [d/l] [select]
Re: Processing a multiple="multiple" <select> by ikegami (Patriarch) on Sep 20, 2007 at 13:38 UTC
Use CGI! Specifically, use `param` in list context. `use CGI; my $cgi = CGI->new(); my @values = $cgi->param('Blah[]');` [download] The problem you have is that you are assigning multiple values to a single scalar (`$POST{'Blah[]'}`).	[reply] [d/l] [select]
Re: Processing a multiple="multiple" <select> by snopal (Pilgrim) on Sep 20, 2007 at 13:47 UTC
There is nothing wrong with not using the CGI module, but it has done most of the work for you. As far as your code, $payload =~ tr/+/ /; should really use a regex to detect multiple parameters, and an assignment to an array. It's going to take additional logic to handle the contents of your payload when the results are not a SCALAR type, as in multiple select results.	[reply]
Re^2: Processing a multiple="multiple" <select> by jpk236 (Monk) on Sep 20, 2007 at 13:53 UTC
Is there any benefit to using s///g over tr///, in this context? I figured that tr/// would be less "expensive" since it's designed to only do character matching. - Justin	[reply]
Re^3: Processing a multiple="multiple" <select> by snopal (Pilgrim) on Sep 20, 2007 at 14:13 UTC
Since you brought it up, 'sed' style matching is too heavy. All you want to do is detect the situation of multiple responses. `if ($payload =~ /+/) { # process as list }` [download]	[reply] [d/l]
Re: Processing a multiple="multiple" <select> by jpk236 (Monk) on Sep 20, 2007 at 13:55 UTC
Great suggestions. Thank you all! - Justin	[reply]

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