F5 causes action to be executed again

[Kevin Stembridge]

Hi Folks,
I'm working on a Struts-based web application that's giving me a bit of grief when the page is refreshed.
For certain actions the user can perform, records are inserted into a database. If the user then refreshes the page, the same action gets performed and another record gets inserted.
How can I ensure that, after submitting an action, the page is not left in a state where the same action will be executed again by refreshing the screen?
Cheers,
Kevin

[Nathaniel Stoddard]

There are lots of solutions to this. One way is to generate a key that goes along with the form data. The key is added to some map when the form is created. When the user clicks once the key is removed from the map. If the user clicks again, you check if the key exists and because it doesn't you don't handle the command.
You could also use a redirect when you return the next view after you handle the form submission. (I think you can do that with Struts.) I don't think there any "out of the box" solutions to this. But hopefully these ideas will get you started on your own solution.

[Kevin Stembridge]

Thanks Nathaniel,
I followed your second suggestion and made a call to response.sendRedirect() just before returning from the Struts Action class.
Worked a treat
Thanks very much.

[Chris Mathews]

Moving to the Struts and Other Frameworks Forum...

[Junilu Lacar]

Actually, there is an "out of the box" solution if you're using Struts. You can use the saveToken(), resetToken() and isTokenValid() methods of the Action class. Redirect may work but I have run into problems using that approach in certain situations (forgot the details but had to do with losing the context).
Basically, you'd have this kind of code in your Action:

// before page is displayed:
saveToken(request);
...
  
// when user submits form:
if (isTokenValid(request)) {
   // process request
   ...
   // processing done
   resetToken(request);
} else {
   // stale or duplicate submission
}

[Marc Peabody]

I agree with Junilu's method. The token is very easy to use and it will also prevent strange things from happening when the user tries using the browser's Back button and resubmitting an out-of-order page.