Problems when refreshing browser

Question

I have created a html form using pl/sql. The parameter of the form are passed through the url to the database. Once information is entered in the form, pressing the submit button inputs the values into the database and refreshes the html page. However, the passed parameters are still in the url and hence when i press the refresh page on the browser, the same values are inserted into the database.
How can I prevent this from happening?

Answer 1

I utilize 3 techniques to prevent double posts:
1. I disable the submit button prior to submitting the page (via javascript). If you do this, note that the button name is NOT submitted with the page parameters.
2. Redirection after the POST to the target page.
3. Add a unique request ID to each POST page. Store submitted unique ID's in an application level collection, and then if that ID is seen again, throw a "page already submitted exception".
Option 1 works well on the client side. But it doesn't prevent the user from right clicking and hitting "refresh" on the result page. Option 2 prevents the right click, refresh. However, at any time, a user can hit Back-Back-Back to get to your form again, at which time they may try to re-submit. For those cases, I also add option #3.
For option 3, I typically put a field such as:
<input type="hidden" name="uniquerequestid" value="<%=strUniqueValue%>">
Every time a request comes through my main handler, I look for the "uniquerequestid" parameter, and if found I check to see if the value has already been submitted. If it hasn't, I add the value to the list of values. If it has, I throw an exception and take the user to a page that says "This page has already been submitted".
Note that the unique request cache list must be stored in the application level, NOT the user session level, else users could hit back as many times as necessary, even when logged in via another user. So I don't store this data in the session.
I then clear my cache list ever few hours, leaving in the most recent ones, and getting rid of old ones.
Hope that helps!
Michael