|Problems? Is your data what you think it is?|
How do I decode a CGI form?by faq_monk (Initiate)
|on Oct 08, 1999 at 00:32 UTC||Need Help??|
Current Perl documentation can be found at perldoc.perl.org.
Here is our local, out-dated (pre-5.6) version:
You use a standard module, probably CGI.pm. Under no circumstances should you attempt to do so by hand!
You'll see a lot of
CGI programs that blindly read from
STDIN the number of bytes equal to
CONTENT_LENGTH for POSTs, or grab
QUERY_STRING for decoding GETs. These programs are very poorly written. They only work sometimes. They typically forget to check the return value of the
In short, they're bad hacks. Resist them at all costs. Please do not be tempted to reinvent the wheel. Instead, use the CGI.pm or CGI_Lite.pm (available from CPAN), or if you're trapped in the module-free land of perl1 .. perl4, you might look into cgi-lib.pl (available from http://www.bio.cam.ac.uk/web/form.html).
Make sure you know whether to use a GET or a POST in your form. GETs should only be used for something that doesn't update the server. Otherwise you can get mangled databases and repeated feedback mail messages. The fancy word for this is ``idempotency''. This simply means that there should be no difference between making a GET request for a particular URL once or multiple times. This is because the HTTP protocol definition says that a GET request may be cached by the browser, or server, or an intervening proxy. POST requests cannot be cached, because each request is independent and matters. Typically, POST requests change or depend on state on the server (query or update a database, send mail, or purchase a computer).