/**
  * Run the validation methods for all the objects being edited.
  * 
  * If this is a form submit then run the validation methods for the default object being edited.  The default method
  * calls the {@link I2CE_Form::validate() validate} method on the {@link $edit_obj} object.
  */
 protected function validate()
 {
     parent::validate();
     if ($this->isPost()) {
         if ($this->last instanceof iHRIS_Salary) {
             if ($this->getPrimary()->start_date->before($this->last->start_date)) {
                 $this->getPrimary()->setInvalidMessage('start_date', 'bad_date');
             }
         }
     }
 }