Question

I am using the Perl CGI module. If I have HTML like this

<select multiple name="FILTER_SITE">
  <option>1</option>
  <option>2</option>
</select>

and submit my form I can get something like this in the URL:
[..] FILTER_SITE=1&FILTER_SITE=2

Perl’s my $FILTER_SITE = $cgi->param('FILTER_SITE'); wil capture only the first instance.

How can I make use of both (in this case)? Hack it and parse the referrer myself and add them to an array is my first idea but it’d be a bit messy, then again I’m hardly versed in CGI.pm or Perl.

With Data::Dumper, interestingly

print "<pre>".Dumper($cgi->param('FILTER_SITE')) . "</pre>";

$VAR1 = '1';
$VAR2 = '2';

Answer 1

NOTE: Current documentation (as of 2020 May 29) says this method could cause a security vulnerability. Please check my answer below.

The param method supplies a single value in scalar context and (potentially) multiple values in list context. Read about it here.

So if you change your code to, for example

my @FILTER_SITE   = $cgi->param('FILTER_SITE');

then the array will contain all selected values of the option.

If it suits your code better, you can also write

for my $FILTER_SITE ($cgi->param('FILTER_SITE')) {
  :
}