Prevent duplicate form submits

 

What is your favorite way of preventing duplicate submits on your forms?

 

Because I do work for Governmental/Political websites, I'm looking for a method that does not "require" JavaScript or Sessions to be passed.

 

I'm really interested in how you all have addressed this issue.

 

Thanks.

 

If what you are asking is to prevent the same user sending more than once, and no session use, then store his IP and datetime of submission, check against this IP every time the form is submited, use datetime to allow him submit again in x hous/days whatever, also note that the IPs are not always given fixed to end users and someone on a dynamic assignment will be albe to submit again if he disconnects and reconnects getting a new IP.

 

Better than all this is to have user registration/login, this way you always know what a particular user can/cannot do.

You're right about the IP issue. I've had as many as 100 users with the same IP on my site at the same time.

 

I was looking for a fool proof way to prevent duplicates on a political website where cookies/sessions and javascript are not to be used.

 

The simplest though not fool proof way I found was a simple redirect on processing.

 

I had an email form and simply used server side validation and then if it the form was good, process the form and then redirected to another page thus preventing the refresh issue. Sure, they could use the back button and submit again but I was only trying to avoid the inadvertent double post.

 

Thanks again.