Can't modify variable received from CGI parameter

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

Weirdness.... I take in a parameter and modify it. When I try to pass it on to another CGI, it doesn't pass....

use CGI qw/:standard/;
use strict;

my $cgi = new CGI;

my $species = param('species');
$species = 'Not Rat';

print
    $cgi->header(),
    $cgi->start_html(),
    $species,
    $cgi->hidden(
        -name    => 'species',
        -default=> $species,
        ),
    $cgi->end_html();
[download]

On screen it displays "Not Rat", but the value in my hidden field is "Rat". What gives? Is this a CGI.pm feature? I scanned the perldoc but didn't see anything like this, but I didn't know what exactly I was looking for....

Comment on Can't modify variable received from CGI parameter Download Code

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Re: Can't modify variable received from CGI parameter by menolly (Hermit) on Sep 09, 2003 at 00:29 UTC
As per the documentation: Note, that just like all the other form elements, the value of a hidden field is "sticky". If you want to replace a hidden field with some other values after the script has been called once you'll have to do it manually: `$query->param('hidden_name','new','values','here');` [download] Add `$cgi->param('species', $species);` [download] at some point before you print the field.	[reply] [d/l] [select]
Re: Can't modify variable received from CGI parameter by benn (Vicar) on Sep 09, 2003 at 10:41 UTC
Altenatively, you could use the '-override' flag, which emoves the stickiness and forces CGI.pm to always use the 'default' value. `print $cgi->hidden( -name => 'species', -default=> $species, -override => 1, );` [download] Cheers, Ben.	[reply] [d/l]
Re: Can't modify variable received from CGI parameter by Anonymous Monk on Sep 09, 2003 at 13:54 UTC
Thanks gentleman, somehow I wasn't thinking this was a function of the field, but of the parameter: I skipped over stickiness without even reading it. The help is much appreciated.	[reply]