Practical Exercise: Data validation

Your trainer will now demonstrate and discuss the use of CGI for validation of data entered into a web form. An example form is in your public_html directory as validate.html and the validation CGI script is available in your cgi-bin directory as validate.cgi.

#!/usr/bin/perl -w

use strict;
use CGI 'param';

print "Content-type: text/html\n\n";

my @errors;

push (@errors, "Year must be numeric") if param('year') =~ /\D/;
push (@errors, "You must fill in your name") if param('name') eq "";
push (@errors, "URL must begin with http://") if param('url') !~ m!^http://!;

if (@errors) {
        print "<h2>Errors</h2>\n";
        print "<ul>\n";
        foreach (@errors) {
                print "<li>$_\n";
        }
        print "</ul>\n";
} else {
        print "<p>Congratulations, no errors!</p>\n";
}