Page has expired

jdh

When I click back in my browser to go back to a php page, I get "Warning: Page has Expired". I am using sessions, and did check session.cache_limiter in php.ini. But it is set to, nocache. Anyone have any ideas?

Eric_Bartels

In my opinion nocache means that these pages are not tempory stored at the clients pc.
So they send a HTTP-Header which says that this page expires immediately. If you click "back" the browser sees that this page has expired.

jayant

Originally posted by Eric Bartels
In my opinion nocache means that these pages are not tempory stored at the clients pc.

You are right Eric 🙂

rinjani

You can add the following to the top of your php page. If you are using session then add it right after the session calls

header("Cache-Control: Public");

This will work for IE but maybe not so well in Netscape 4.x

HTH

dannys

"Warning: Page has Expired" - this is usually caused by trying to go back to a page which has posted form data, it's got nothing to with caching (AFAIK).

If you really need to get around this then use GET as the form's method instead of POST.

jayant

Sorry dannys, you are incorrect.

Any page can be expired.
Moreover you can also do that form posted using POST don't get expired 🙂

All can be achieved thru Expires header.

devarticles

using the get method, can be a VERY big security risk, only use it if you really need to. You increase your chance of someone seeing other peoples data!

Eric_Bartels

POST-Method isn't very secure either 🙁

dannys

Originally posted by jayant
Sorry dannys, you are incorrect.

Any page can be expired.
Moreover you can also do that form posted using POST don't get expired 🙂

All can be achieved thru Expires header.

Ok show me a non form page which produces that error.

devarticles

POST-Method isn't very secure either

LOL, its alot more secure then GET, esp when you have hidden values.

dannys

It's not that much more secure - what's to stop me from using one of the many http-client php classes to submit a POST request using modified form variables.

Fact is, you shouldn't be passing sensitive data around using forms in the first place - use sessions (store the data on the server, much better) or set a cookie (security is still a concern but you can encypt, encode and/or sign it)

jonno946

Sorry for interrupting in someone elses post, but this question kind of links into the origional one.

I load a page in my browser, and it loads. However, if i go and visit that page again, it annoyingly retrieves the data from the cache. How can i force a page to refresh each time its loaded?

jayant

Originally posted by dannys

Ok show me a non form page which produces that error.

make any normal HTML page form php but use

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

first, now follow any link on the page and hit browsers back button, it will say you page expired 🙂

http://www.php.net/manual/en/function.header.php

jayant

Originally posted by jonno946
Sorry for interrupting in someone elses post, but this question kind of links into the origional one.

I load a page in my browser, and it loads. However, if i go and visit that page again, it annoyingly retrieves the data from the cache. How can i force a page to refresh each time its loaded?

PHP scripts often generate dynamic content that must not be cached by the client browser or any proxy caches between the server and the client browser. Many proxies and clients can be forced to disable caching with :

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");    // Date in the past
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); 
                                                     // always modified
header("Cache-Control: no-store, no-cache, must-revalidate");  // HTTP/1.1
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");                          // HTTP/1.0

Lifted this shamelessly from the PHP Manual which the people forget to look into.

ShawnD

to see if it really is a caching error, go to my site here , click on a link on the left then click back. my site has nothing more in terms of php than include('whatever').

from my own experience, i've only got the error of the page expiring when i've had to send data to a website (such as posting in a forum) and the website doesn't respond for a second, i'll push reload and it will say 'this page has expired' because it's a page you are sent to after you click to post the message then it sends you back to the thread you were in before. since i pushed reload, it doesn't register as me being refered to that page from the forum so it doesn't know what to do.

jayant

Originally posted by ShawnD
to see if it really is a caching error, go to my site here , click on a link on the left then click back. my site has nothing more in terms of php than include('whatever').

from my own experience, i've only got the error of the page expiring when i've had to send data to a website (such as posting in a forum) and the website doesn't respond for a second, i'll push reload and it will say 'this page has expired' because it's a page you are sent to after you click to post the message then it sends you back to the thread you were in before. since i pushed reload, it doesn't register as me being refered to that page from the forum so it doesn't know what to do.

When you click back button, you do not get this error 'coz you are not expiring page views.

piersk

This is going back to Jayants last post here...

I thought that you could only have one header() in each page cos the browsers dont like it if you have more than one...

dannys

Nope, you can have as many headers as you like - as long as they all appear before anything is output to the browser.

jdh

The header:

header("Cache-Control: Public");

worked perfectly. Thank you.