RE: Re[5]: [PHP-WIN] Preventing multiple submits

Success! Thanks to Zak and the others who have helped me on this matter. I now have a very basic "session" working, which will allow me to check for multiple form submissions, etc. I have some basic questions about sessions that aren't that obvious (to me anyway) from the PHP manual: 1) A PHP session uses a cookie file that is stored on the server (in the directory specified in the PHP.INI file)? 2) No files/cookies are written on the client side when using PHP sessions? 3) I can use session declared variables to transfer values between web pages rather than passing them via the URL (which will prevent the URL getting cluttered)? 4) How do I delete the session files created? For example, "session-destroy" doesn't delete them? 5) If the user closes their browser before I destroy the session I assume the session is automatically closed? 6) If the user closes their browser before I delete the session cookie file how do I track/delete redundant cookie files from the server? 7) You can only have 1 session open at any one time? If anyone could answer these questions it will greatly help my understanding on this matter. Thanks James -----Original Message----- From: Zak Greant [mailto:zak@php.net] Sent: 25 August 2000 17:31 To: James Duncan Cc: Pablo Vera; php-windows@lists.php.net Subject: RE: Re[5]: [PHP-WIN] Preventing multiple submits Hi James, Something like this should work: session_register ($form_submitted, $mail_sent); $form_submitted++; if (! $mail_sent) { $mail_sent = mail ($to, $subject, $message); } else if ($form_submitted > 1) { echo "Please do not press the submit button more than once.) } - zak At 04:57 PM 8/25/00 +0100, James Duncan wrote: >Folks, > >Please ignore my previous email about my feeble attempts to track the >multiple submitting of a form using PHP. I have accomplished this via >writing a variable to a text file and then reading this in each time and >incrementing it, etc. If the value is greater than 1 then the form has >already been submitted. I can check for this value each time my PHP script >runs and perform the necessary action depending on the value. > >Of course this is only a temporary solution because it only works in a >single user environment. I need to look at sessions and "session_register" >in particular it seems! Do the "session" features require that the client >can accept cookies? For example, if cookies are disabled on the client do >"sessions" still work? Are they server-side only? The whole point of this >exercise is to find a server side only solution to preventing a user >submitting the same form multiple times. > >However, I already have the same problem as Pablo, in that the browser only >displays the output from the last script ran, which if the user hits the >submit button more than once is a message saying "You have already submitted >this form" rather than the intended message of "Email has been successfully >sent". > >Is there an easy way to get PHP to immediately clear the screen at the start >of a script, without waiting for the rest of the script to finish >processing? If so then I can clear the screen immediately after the user >clicks the submit button, which would prevent the user from going mad with >the submit button! > >Thanks > >James > > >-----Original Message----- >From: Pablo Vera [mailto:pvz@vercan.com] >Sent: 25 August 2000 15:40 >To: Zak Greant >Cc: James Duncan; php-windows@lists.php.net >Subject: Re[5]: [PHP-WIN] Preventing multiple submits > >Zak: > >You are COMPLETELY RIGHT !, I did some checking and by registering a >variable (with session_register), it will keep its value from script >to script. I only have one problem, when the user submitts a second >form, the browser will cancel the first connection. The first script >will run normally, but its output (confirmation, error, etc.) will not >reach the browser. The user will only see whatever the second script >sends. If there was an error in the first one, he won't know. How do >you solve this ? > >Saludos, >Pablo Vera >_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ > >Thursday, August 24, 2000, 5:22:08 PM, you wrote: > >ZG> At 05:11 PM 8/24/00 -0500, Pablo Vera wrote: > >>[snip] > >>Zak: > >> > >>I think that the "if (! $post_counter)" will always result in a true > >>condition, this is because the only ways to preserve a variable from > >>instance to instance of a script is by sending them in the URL or by > >>setting a cookie, but since the form is being submitted twice from > >>exactly the same page, you will have two scripts running at the same > >>time, with exactly the same variables and values, and the output of > >>the first one will not be received by the browser, because the second > >>one canceled that connection. You will end up processing two forms, > >>but the user will receive confirmation for only one. > >ZG> The $post_counter variable is not stored client side. All that you >store >ZG> client side is a session id in either a cookie or as get/post data. > >ZG> The $post_counter variable is tracked server side by PHP's session >manager. >ZG> (You could also use another mechanism, if desired.) > >ZG> - zak