Prevent multiple form submits with PHP

[thirdearth]

Hi there.  I've been working on a PHP-based web game for quite some time that is coming out great, but I have run into a problem.  A lot of the aspects of the game involve clicking "submit" form buttons, and use a PHP isset command to update the mysql database based on what you clicked.

 

Example if I was trying to go North:

 

<form name="form" action="playerhome.php" method="post">
<input type="submit" name="north" id="north" value="North" />
</form>
<?php
if (isset($_POST["north"])) {$longitude--;
$herodirection = "heroup";
mysql_query("UPDATE members SET herodirection = '$herodirection', y='$longitude'  WHERE login = '$login'");
header('Location: playerhome.php'); }
   }
?>

 

Its more complicated than that, but not relevant to my question.  The problem is that while everything works great if you single click around in the game, problems arise when people click any buttons in rapid motions and start getting multiple clicks in before the form refreshes the page.  I thought I could use the javascript disable function to disable the button after it was pressed, but when I did that, any PHP within the isset command would no longer run.  Can anyone think of a way with PHP to prevent multiple submits?

[Alex]

Here's what you can do, JavaScript will work.

 

var form_submitted = false;

function submit_form ()
{
  if (form_submitted)
  {
    alert("Your form has already been submitted. Please wait...");
    return false;
  }
  else
  {
    form_submitted = true;
    return true;
  }
}

 

Then within your <form> element add onsubmit="return submit_form()"

[thirdearth]

Thanks.  The alert popping up is annoying, but the idea itself worked like a charm!