About 'resend form information' when i hit 'BACK' button

[agun]

Hi, guys

sorry if this kind of question had been asked before and kinda newbie question. coz i'm new to programming and just couldn't figure it out yet...

My problem is:

I have a form that POST variables and execute function in the target page (That function happens to be sending email).
If i hit the back button, the browser asks me if i'd resend the information again. And thus, the email would be sent again.

My question is:

Is there any best practice or some kind of techniques to overcome this tipical problem? Coz i know disabling the BACK button would be very bad idea and i don't like it either.

I tried to capture the isset(POST['submit']) parameter so that the code would only executed if i ACTUALLY hit the SUBMIT button.

But, apparently, the BACK button is somekind like 're-doing' my actions (as if i was actually hit the submit button)

I tried the history.go(1) techniques, but it only works in IE. I want it works for cross browsers.

Thanks alot...

[iam_clint]

There is a way to do this if I remember correctly you do it as follows
page a -> post to pageb -> transfers you to pagec without writing anything
and in this method when you hit back it goes from pagec to pagea.. and doesn't want to retransmit the data.

[Atli]

I was working on a similar problem the other day.

What I did was create a random string (a hash), which I stored in a session variable and echoed into a hidden <input> element in my form page.

Then, once the data had been submitted, I had my action page match the session variable to the value of the <input> element. If they matched, I unset the session variable and processed the form. If they didn't I simply redirected the user back to the form page.

This only allows each form to be submitted once, requiring a new random string for each submission.

[agun]

Thanks Clint and Atli,

You've been really helpful. Now i have a slight idea about how to do it. I'll try your suggestion.

Thanks

[agun]

wow, thanks Clint and Atli,

I tried your suggestion, i make random number, store it in session variable, pass it to hidden input element in the action form and in the action page i compare with the POST variable. and it works!

So, if user hit BACK button, it won't be a problem now, coz the session doesn't match with the POST.

Thanks guys...

[acoder]

In case you're interested, the method Clint was referring to is Post/Redirect/Get (PRG).