[SOLVED] Help with headers and Back Button please

[Riparian]

Scenario :

 

I add a product to the cart with a href call with the model number included.

 

e.g. <a href=$_SERVER[php_SELF]?model=1234>Add to cart</a>

 

On the page re-load model 1234 is added to cart. All fine so far...

 

The client then clicks to go to the cart

 

e.g. <a href=cart.php>Cart</a>

 

Problem.....

 

If the client uses the Browser Back Button this URL reloads

 

<a href=$_SERVER[php_self]?model=1234>Add to cart</a>

 

Which adds another entry into the cart. How can i prevent this ?

 

Any help is greatly appreciated

[Ken2k7]

Two things you can do:

1. Don't use links to add data.

2. Check if the model exists. If so, don't add it.

[Riparian]

Thanks for the input

 

Unfortunately both are not possible as I offer up to 100 products per page so I do not see how this be achieved any other way and  a client is at liberty to add 2 of the same model number to the cart ( 2 must be added individually for later processing)

 

Is there no other way ?

[Riparian]

I have figured a work around.

 

Only record an entry if a session variable is set in the add program.

 

Unset the session variable in the cart program so if they use the browser back button the entry will not be re-recorded.

 

Unless anyone can see a downside to this method then perhaps this will help someone else.

 

Cheers