Separation between View and State (The Back Button)

[Michael B Allen]

Let's say you have a "Buy" botton that posts a form to a script that
inserts or increments the quantity of a record in a shopping cart
table. So you click "Buy" and then "Checkout". Now if you hit the Back
button it asks the user if they would like to repost the form. If they
click "Ok" the db script runs again and now they have two items in
the cart.

It seems to me this is a fundamental model view controller kind of
problem. There's no seperation between the view and the controller. Can
someone recommend a generic method for providing that seperation? I could
have the script emit a Location header but that's a strange hack. What
is the definitive method for solving this probably very common issue?

Thanks,
Mike

[Vincent van Beveren]

It seems to me this is a fundamental model view controller kind of

problem. There's no seperation between the view and the controller. Can
someone recommend a generic method for providing that seperation? I could
have the script emit a Location header but that's a strange hack. What
is the definitive method for solving this probably very common issue?

I don't see how JavaScript would solve this problem. Generally you'd do
a redirect after a submit. Because the redirect is not a POST the
browser forgets the post. Doing a back will cause you to go back to the
page which was requested with a GET, thus no repost. I think you can
better ask this question on a server-side-something form, like Servlets,
PHP or ASP.

Cheers,
Vincent