code: def post(self):
      
      client_customer_id = self.request.get('clientCustomerId')
      budget_id = self.request.get('budgetId')
      if not client_customer_id or not budget_id:
        self.redirect('/')
      else:
        self.redirect('/showBudget?clientCustomerId=%s&budgetId=%s'
                      % (client_customer_id, budget_id))
docs: Handle post request.