Webmaster Forum / ColdFusion / Getting Started / January 2008

Nothing is foolproof, but ip address is as good a way to go as any.

Hi,
    you can try using session variable to keep track of the form submission.

Prasanth

If you're just trying to prevent a double-click form submission, use
CreateUUID() in the session as a ticket and then pass that in the form.  When
the form is submitted, compare the form value against the session ticket value,
if they match, then regen the session ticket and process the form, that way if
they double submit the form, the resubmission will not match the regenerated
ticket.

If you're trying to set a limit, such as one entry per day, etc... I'd suggest
implement some type of authentication user/password with a persistent user
record.  Cookies can always be cleared as well as munging the header info.  
eMail addresses are cheap.  It all depends on just how much you want to lock
down the submission.  You can even go the captcha route (letters/numbers in an
image that have to be entered) to limit script submissions

Rking1966 wrote
[i]I am wondering about cookies...[/i]

You got me wondering, too. I thought of something like:

formPage.cfm
============
<cfif isDefined("cookie.isFormSubmitted") and cookie.isFormSubmitted>
You have already submitted the form. You may only do so once.<br>
<p>
<a href="someOtherBusinessPage.cfm">To business</a>
</p>
<cfelse>
<form action="actionPage.cfm" method="post">
<input name="field1" type="Text">
<input name="send" type="Submit" value="Send">
</form>
</cfif>

actionPage.cfm
=============
<cfif NOT isDefined("cookie.isFormSubmitted")>
<cfcookie name="isFormSubmitted" expires="never" value="true">
</cfif>

<!---
Business code to handle submitted form fields
 --->

Thanks for the suggestions. Cookies does seem pretty easy. This doesn't have to
be foolproof. No one will go through the trouble of clearing cookies, etc. We
just want to have valid data for our study and avoid having folks forget they
had already completed it and do it again.....these are college students.

Thanks,
Richard

I hope you are allowing the form after the user logged in. If that would be the
case then you can set a flag in the database to check whether this particular
user has already submitted the form. If so then don't allow.

If you're just trying to prevent a double-click form submission. By using
javascript you can prevent the user by clicking please go through the below
website.

http://www.web-source.net/web_development/form_submission.htm.

You may also check against the unique ID for e.g. email id. but again with
different email id the form can be submitted.

Please explain the business scenario for which you are trying to implement.

Hope this helps.
Thanks,
Satheesh.