PHP-缓存控制在我的情况下不起作用

Question

i need some help, i got a php file which is called shoppingcart.php and the data of chosen product will post to this page for sql insert, and if i reload this page by f5 or press "Backspace" at next page, the same data will re-insert again so i don't want this to happen and been doing some searching but still not solving my problem.

My Code:

<?php
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?>

<?php
if(isset($_POST["form"])){
//insert data to db
}

ob_start();
?>

<form id="form" name="form" method="post" action="<?php echo $_SERVER["PHP_SELF"]; ?>"
enctype="multipart/form-data" onsubmit="return validate();">
....
....
....
</form>

<?php
$pagecontent = ob_get_contents();
ob_end_clean();
$pagetitle = "Shopping Cart";
include("include/template.php");
?>

I have researched on output buffer and http header article but i still can't figure it out why it is still happening. Please help me~ Thanks in advance.

Answer 1

Try putting all your Cache-control headers into the same call to header() . The browser may not be expecting multiple Cache-control headers.

Also, are you getting a prompt in the browser that reloading will resubmit POST data? If so, and you are electing to resubmit, you will need your own code to ensure that force-rePOSTed data is rejected (despite the user's request), eg. by including a unique identifier in the form that is checked before re-inserting. Alternatively you can accept that if the user elects to resubmit POST data, then they are explicitly requesting that the request be re-processed.