How are you detecting postback?

[eluser]BrianDHall[/eluser]
I check for some specific required field, usually the most 'obvious' one, and I also have the tendency to put hidden fields in my forms that I check for to be definitive on just what form is being submitted. Some forms I actually use this to handle form submission in my constructor or MY_controller (I handle login this way, so if there is $this->input->post('login_request') is true I try to log the user in before doing anything else). The advantage there is that I can build any form, anywhere on the site, in any way I want and have it 'just work' so long as I stick the right hidden form field or even drop-down field option in a form somewhere.