Serving Perl Pages to the Web - Learning MySQL - page 562

Note that the CGI function to create a table row is Tr( ) rather than tr( ) ; this is to
avoid confusion with a completely different “transliteration replacement” function tr
that is available by default in Perl.
Processing User Input
User interaction with a web application is typically a two-way affair; the system displays
content to the user, who provides input, such as through a web form, that the system
uses in further processing. For example, an online store application displays items for
sale; the user chooses items and enters purchase information, and the system displays
a receipt.
For our pet roll call example, we could allow the user to enter the name of an animal.
The system could then process this information and return the number of animals of
that type. This requires two web pages. First, a form is displayed to accept user input.
When this form is submitted, a second page is displayed with the query result.
You can generate an HTML form that passes the submitted values to the proc-
ess_form.pl file using the HTTP POST method by writing:
print
start_form(-action=>"process_form.pl", -method=>'POST').
...form content... .
end_form;
Example 18-4 generates a web form with a simple text input field.
Example 18-4. A CGI Perl script that generates a simple form
#!/usr/bin/perl
use strict;
use CGI ':all';
print
header(-type=>"text/html", -charset=>'UTF-8').
start_html(-title=>"Search Page", -encoding => 'UTF-8');
if(param())
{
print "<br />The string you entered was: '".param('query')."'";
print "<br />Dumping all the submitted data...";
foreach my $Name (param())
{
print "<br /><b>$Name: $Name);
}
}
else
{
#start_form can take -action, -method...
print
start_form.
"Query String: ".