@Override public Navigation run() throws Exception { Validators v = new Validators(request); v.add("id", v.longType()); v.add("salary", v.required(), v.integerType()); if (!v.validate()) { System.out.println("validation error: " + errors); return null; } long id = asLong("id"); int salary = asInteger("salary"); Key key = Datastore.createKey(Employee.class, id); Transaction tx = Datastore.beginTransaction(); try { Employee e = Datastore.get(tx, Employee.class, key); e.setSalary(salary); Datastore.put(tx, e); tx.commit(); } finally { if (tx.isActive()) { tx.rollback(); } } return forward("updateSalary.jsp"); }