Re: Server-side Form Validation (Perl)

--- Quackamoe <quackamoe(at)yahoo.com> wrote:
> All the examples of form validation* I can find
> use JavaScript. I'd like to use Perl instead so
> I don't have to worry about somebody having JS
> turned off. (And because I know Perl a bit more
> than JS.) ;) Even Lincoln Stein's book uses
> JS for this.

Usually, most of the hardest work is validation, and
the rest is just fun (mailing form input, inserting a
row of data in a database or building a query or
whatever).

I agree that if you're serious about validation, you
obviously HAVE to do it server-side.

I've experimented with different techniques to make it
efficient, but don't claim to have it down. I've
stolen freely from more people than I can remember,
and hvae added a few twists of my own. 

I recently wrote a Perl script that among other things
collected contact info from the user for insertion in
a database. I decided to create a multidimension
array, each of whose elements was a list consisting of
the form field's name/label, field length, max length,
and option default value. I called my required fields
"* Fieldname", and put the array elements in order of
appearance on the page. This way I could call a
function to print each row of my table/form like so:

for  (   @contact_fields ) {

		printrow(@{$_});
     }

Here's how printrow looks:

sub printrow {

   my ($field, $size, $max, $default) = @_;       
   my $label = $field;
   $label =~ s/^\*/<font color="red">*<\/font>/;
   print qq(<tr><td align="right">$label</td><$td>),
		textfield(-size=>$size, -name=>$field,      -value
=>param($field)? param($field) : $default,     
-maxlength=>$max), "</td></tr>";
}

----------------------------------------------------

BTW you have to have loaded CGI.pm for the textfield()
function above

When it came time for validation, I did the following.

Note the use of the Email:Valid module for checking
for a well-formed email address.

----------------------------------------------------
my @required;
my @booboos; # or should I call it @crimes?

foreach my $field (@contact_fields) {      
    if ($field->[0] =~ /^\*/) {
        push (@required, $field->[0]);
     }
}

for (@required) {
    if (!param($_)) {
        s/^\* //;
        push (@booboos, "Your $_ field is blank") ;
	$err++;
     }
} # easy, huh?


#  requires the Email::Valid module
if ( param('* Email') and                 
!Email::Valid->address(param('* Email')) ) {

    push (@booboos, param('* Email') . " does not look
       like a valid email address");
    $err++;
}

if (  my $url =  param("Web site") ) {

    if ( $url =~ /\S+\s+\S+|[@;]/ ) {
        $err++;
        push (@booboos, "$url does not look like a    
             valid URL");

     }
}

##  password check (they're supposed to create a 
##  password and confirm it)

if ( !param('passwd') && param('passwd2')) {
        $err++;
	push @booboos, "You did not enter a password";
}
if ( param('passwd') && param('passwd2')
	&& param('passwd') ne param('passwd2') ) {
        $err++;
    	push @booboos, "Your 'confirmation' password     
      does not match your password";
}
if ( param('passwd') && !param('passwd2') ) {
        $err++;
        push @booboos, "You did not re-enter your     
           password for confirmation"
}
if ( !param('passwd') && !param('passwd2') ) {
    $err++;
    push @booboos, "You did not enter a password      
      and reconfirm it."
}

if ($err) {   

    $errmsg  = "I can't accept your form because: "
		. ul( li (\@booboos) ) . "Please scroll           
down and try again.<br><br>" ;
				                print_contact_form($errmsg);   
    exit;
} else {

# do your thing with the data they gave you
# and tell them to go have a nice day

}

      David

David Mintz
Spanish Interpreter, US District Court
Southern District of New York
Web Design & Hosting http://www.dmintzweb.com
Personal http://www.panix.com/~dmintz

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