Re: browser back-button problem

thanks a lot for this answer, it was really helpful. unfortunately the problem is not solved entirely: if the browser back-button is hit, the actions are not executed twice, but still the old data is displayed. what I did: I put my code in tow seperat files: 1: display the file and refert to the second file, if submitted 2: do delete, do new. here the checksum is evaluted, so these actions are only executed if they have not been executed before. works fine. thanks. BUT if the browser back-button is used, the browser jumps back to the the (old) #1 files with their contents to this time, meaning you dont see the actual contents, but older ones. moreover, if now any action is called, it is not executed, instead the #2 refers directly back to #1 (as checksums are not identical) and displays again. this time the actual content. although no errors can happen anymore, I find this a little confusing for the user. what can be done to either force the #1 to be executed again on browser back or show some "expired" message? thanks in advance marcel "Jonathan Sharp" <js-lists@sharpmedia.net> schrieb im Newsbeitrag news:3DADB109.2060105@sharpmedia.net... > Take an md5 of the entire file contents and store that in your form that > get's displayed. Then test if it matches the file when you go to make > the changes. Every time you change the file the md5 will change. See > below... > > -js > > Sample script: > <? > $file = file('/your/text/file.txt'); > > if ( $_POST['doSomething'] ) > { > // Make sure it's the same file: > if ( md5( implode('', $theFile) ) == $_POST['checksum'] ) > { > // Code to change the file (add/delete etc) > } > else > { > echo "File has been changed, aborting modifications."; > } > } > else > { > // Just show the file > ?> > <form...> > <input type="hidden" name="checksum" value="<?=md5( > implode('', > $theFile))?>"> > <input type="submit" name="doSomething" value="Do > something"> > </form> > <? > } > ?> > > marcel wrote: > > hi there > > I am kind of a newbie to php > > so probably I am doing it all the wrong way - if - please tell me > > > > ok heres my problem: > > the script: > > I have a user-group-administration script (php4), that loads data from > > a textfile and then eables the admin to delete or create new user-passwords. > > the script retreives the text data from the text-file and displays the > > entrys. > > to every entry there is a delete-button, that sends the number of the entry. > > and there are formfields and a new-button that sends the new data. > > the script that is called is the same script as the one that does the > > displaying, > > e.g. depending on the sent variables the script delets or creates an entry > > then displays the new data. > > > > the problem: > > if someone uses the back-button of his browser, the data is transferred > > again ( at > > the moment I do it with POST out of the form), and the actions are executed > > again. > > e.g. when the user created a new entry, verytime he hits the back-button > > will create > > a new - similar - entry. > > > > How can I prevent this? > > I saw several forms, that displayed this: "form is expired" thing, if you > > used the back-button (?). > > > > > > thanks a lot > > marcel > > > > > > > > >