满足条件时如何使CGI输入字段返回其初始状态（CGI.pm/Perl）

Question

I have a CGI script that looks like this.

#!/usr/local/bin/perl

use CGI ':standard';

print header;
print start_html('A Simple Example'),
h1('A Simple Example'),
start_form,
"What's your name? ",textfield('name'),
p, submit, end_form,
hr;

my %unwantedwords = {'foo' => 1 };

if (param())
{
    my $text =param('name');

    # I attempted this to but failed.
    unless ($unwantedwords{$text}){
        print  "Your name is: ",$text,
   }
    hr;
}
print
end_html;

What I want to do is basically to receive a text via 'textfield' and then print it out on the web. But when a word inserted by user is an unwanted words (stored in the hash), instead of printing it I'd like the web to return to it's fresh initial state.

What's the best way to do it? The above code doesn't work.

Answer 1

Something like, (Untested)..

use strict;
use warnings;
use CGI qw( :standard );
use CGI::Carp qw( fatalsToBrowser );

my @unwanted = qw( foo bar baz );

my $text = param('name');

print header,
      start_html('A Simple Example');

display_form() and exit unless !grep($text eq $_, @unwanted);

print "Hello $text\n";

sub display_form {
   print start_form,
         h1('A Simple Example'),
         qq( What's your name? ), textfield(-name => 'name', -value => '', -override => 1), p,
         submit, hr,
         end_form;
}

print end_html;

Answer 2

You'll need to save the state of the word before it is submitted, and retrieve it to send back if the submitted word is on your list of bad words.

Your implementation will differ depending on your persistence engine, but regardless of whether you use a cookie to store the old word, or use a session store, you'll do something like this:

 1. store the old word

 2. send the old word along with the web form.

 3. receive new word back

 4. if (new word is in the bad word list) {
      get the old word from storage
    }
    else {
      store the new word
    }

 5. do what comes next