Defining global conditions in Model

Question

Is it possible to define global conditions for Model ?

I have 2 Models: User and Student. In database both of them are using table u

Answer 1

you could use the afterFind callback to alter your finds in the model

public function afterFind($results, $primary = false) {
    foreach ($results as $key => $val) {
        if ($val['parent_id'] == NULL) { //no parent_id set then remove that part of the results
           unset($results[$key]);
        }
    }
    return $results;
}

reference: http://book.cakephp.org/2.0/en/models/callback-methods.html