how to get POST values in perl - perl

Question

I am trying to customize a script and need to get a POST value from a form using perl.
I have no background of perl but this is a fairly simple thing so I guess it should not be hard.
This is the php version of the code I would like to have in PERL:
<?php
$download = ($_POST['dl']) ? '1' : '0';
?>
I know this may not be at all related to the PERL version but it could help I guess clarifying what exactly I am looking to do.

Answer 1

Well, in that case please have a look at this simple code: This would help you:
#!/usr/bin/perl
use strict;
use warnings;
use CGI;
use CGI::Carp qw(fatalsToBrowser);
sub output_top($);
sub output_end($);
sub display_results($);
sub output_form($);
my $q = new CGI;
print $q->header();
# Output stylesheet, heading etc
output_top($q);
if ($q->param()) {
# Parameters are defined, therefore the form has been submitted
display_results($q);
} else {
# We're here for the first time, display the form
output_form($q);
}
# Output footer and end html
output_end($q);
exit 0;
# Outputs the start html tag, stylesheet and heading
sub output_top($) {
my ($q) = #_;
print $q->start_html(
-title => 'A Questionaire',
-bgcolor => 'white');
}
# Outputs a footer line and end html tags
sub output_end($) {
my ($q) = #_;
print $q->div("My Web Form");
print $q->end_html;
}
# Displays the results of the form
sub display_results($) {
my ($q) = #_;
my $username = $q->param('user_name');
}
# Outputs a web form
sub output_form($) {
my ($q) = #_;
print $q->start_form(
-name => 'main',
-method => 'POST',
);
print $q->start_table;
print $q->Tr(
$q->td('Name:'),
$q->td(
$q->textfield(-name => "user_name", -size => 50)
)
);
print $q->Tr(
$q->td($q->submit(-value => 'Submit')),
$q->td(' ')
);
print $q->end_table;
print $q->end_form;
}

Answer 2

Style advice: you almost never need to assign 0 or 1 to a variable. Simply evaluate the value itself in bool context.
In CGI.pm (CGI), the param method merges POST and GET parameters, so we need to inspect the request method separately:
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use CGI qw();
my $c = CGI->new;
print $c->header('text/plain');
if ('POST' eq $c->request_method && $c->param('dl')) {
# yes, parameter exists
} else {
# no
}
print 'Do not taunt happy fun CGI.';
With Plack::Request (PSGI), you have different methods for POST (body_parameters) and GET (query_parameters) in addition to the mixed interface (parameters):
#!/usr/bin/env plackup
use strict;
use warnings FATAL => 'all';
use Plack::Request qw();
my $app = sub {
my ($env) = #_;
my $req = Plack::Request->new($env);
if ($req->body_parameters->get_all('dl')) {
# yes
} else {
# no
}
return [200, [Content_Type => 'text/plain'], ['Do not taunt happy fun Plack.']];
};

Answer 3

Here's a good place to start: The Fool's Guide to CGI.pm,
the Perl module for CGI scripting.
This will show you "...how to get the POST value (from a submitted form) and assign it to a variable."
Hope this helps!

Answer 4

The above examples are bit complicated. The below code reads POST values into a variable. You can extract Key Value from that. If its GET then its better to use CGI module.
#!/usr/bin/perl
my $FormData = '';
read(STDIN, $FormData, $ENV{'CONTENT_LENGTH'});
## Variable $FormData holds all POST values passed
use CGI;
my $cgi = new CGI;
print $cgi->header();
print "$FormData";