posted 20 years ago
I've seen this with the help of javascript.
You can use the onChange attribute of your select tag to call a javascript which submits the form, so that it can be populated by an appropriet action class.
The thing you have to recognize is whether it's the final submit of the whole form, of if it's only a partial submit to fill out some other fields. This can be solved by setting a hidden field to a particular value.