Hi,

It is simple possible using define _constraints for that field. In that you can define python function to manage validation. So, you can manage as you want llike value shouldn't "0" or value must follow any special pattern. You can define your validation as like below.

_constraints = [ _check_function, "Message of wrong entry", ['field1','field2', ... ] ]

def _chech_function(self, cr, uid, ids, context=None):

    //Your code to manage entered record.

    //You can return True to allow entered record or you can return False to deny entered record.

I hope this will help you.