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So far we have seen how...
Perl can produce the an HTML mailing list form using a multi-line print statement
So what does the...
Mailing List Form look like when written using CGI.pm?
Each of the three mailing list forms we have looked at pass their form information to the same Perl cgi script so it is about time that we had a look at...
#!/usr/local/bin/perl -w
# maillist1.pl - k.mcmanus@gre.ac.uk 20000915,20011017,20021109
# Mailing list example CGI program:
# accepts data from a form
# logs it to file for later processing by a separate batch program
# returns confirmation of the data to the user
use lib ('/home/mk05/perl/lib');
use MyTime qw(dtstamp);
use CGI qw(:standard);
use Fcntl qw(:flock);
# Save the data into mlist.txt
open(MLISTHANDLE, ">> ../comp1037/perl/mlist.txt");
flock(MLISTHANDLE, LOCK_EX);
print MLISTHANDLE dtstamp('compact'), ":", param('Email'), ":",
param('Title'), " ", param('Initials'), " ", param('Surname'), ":";
foreach $val(param('Platforms')) { print MLISTHANDLE $val, " " }
print MLISTHANDLE "\n";
flock(MLISTHANDLE, LOCK_UN);
close(MLISTHANDLE);
# Return confirmation
print
header(-type =>'text/html',
-expires => 'now',
-charset => 'UTF-8'),
start_html(-title => 'Results from mailing list program maillist1.pl',
-style => {-src => '../comp1037/perl/mailform.css'}),
h2('The following details about you are now held on our mailing list:'),
"\n Title: ", param('Title'), br,
"\n Initials: ", param('Initials'), br,
"\n Surname: ", param('Surname'), br,
"\n Email: ", param('Email'), br, br,
"\n Platforms: ", br;
foreach $val (param('Platforms')) { print " ", $val, br }
print
hr, "\n", a({-href => "$ENV{HTTP_REFERER}"}, "Return to the previous page"),
br, "\n", a({-href => "../comp1037/perl/mlist.txt"}, "Look at the mailing list"),
hr, end_html;
Debugging code such as this is not helped by an error message in a browser reporting an internal server error but giving no details. It can be helpful to run the code in a shell, preferably a Unix shell. At the command prompt simply type the name of the script and provide the form data as a list of space delimited name=value arguments. You even get to see the HTTP header. CGI.pm recognises the Perl -debug pragma. See the documentation for other useful tricks.
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