Drupal forms and redirection

You've created a form through the forms API, and because you want some custom behavior, you need it to post back to you... so why does you get a 302 redirect when trying to process it?!

If you don't know about this little... well ackward behavior, chances are you don't need to do anything -- you're using the FAPI the way it was meant to be used. If, on the other hand, you want to do something more, you get  a nasty redirect that avoids all the processing you want to do to your form (like redisplaying itself with more data appended, as in a simple search form).

It appears to be a little hidden gem within the Drupal Forms API -- you can set 


So that the form does not generate a redirect code, but executes its hooks normally. Just so that someone else avoids the hairpulling this caused on this side.