Re: Preventing multiple submits

Correct me if I'm wrong on this, but I think a cookie has
to make a round trip back to the client to be set, so that
would not prevent resubmits if the user clicks again while
the original request is still processing.

Another low-tech-ish way to deal with this would be to have
your app code check the database before inserting a new record
for entries from the same user along with some distinguishing
feature of the item -- for example, if it were a BBS post,
you could check the Subject line; for a user account entry,
you could concatenate FirstName + LastName  -- and set a time
window, say two minutes.

So, in short -- if:
Same user creating the entry
Same FirstName + LastName
In the last two minutes

You could safely assume that it's a re-post , and you could
return an error to users notifiying them that they are
attempting a duplicate post.

This might be a nice fallback is the user has JavaScript turned
off, and you can't just disable the Submit link after a post.


Matthew



On Thu, Feb 17, 2005 at 10:40:24AM -0800, the entity known as [email protected] wrote:
> Andi Scharfstein,
> 
> On Thu, Feb 17, 2005 at 12:39:22PM +0100, Andi Scharfstein <[email protected]> wrote:
> > Hi,
> > on my website, there is a form where users can submit data to the
> > site. I was just wondering if there was a simple (server-side) way to
> > check if the user has already submitted something and preventing him
> > from submitting the same thing twice (because he clicked on 'Submit'
> > multiple times because the site took a little longer to load, or
> > something along those lines). Can you achieve this in mod_ruby without
> > resorting to more than moderately complex measures?
> 
> You could use a cookie.
> 
> When form is submitted, check for cookie.  If set, assume it is a
> resubmit.  If no cookie is present, assume it is a new submit and
> then set a cookie to prevent another submit.
>