Question

While trying to learn Play Framework I ran across the following problem:

How do I calculate the summary for a field in a Play Framework Model? I would like to do the equivalent to SQLs “SELECT SUM(totalAmount) FROM events where employee_id = 23”.

I could count the summary myself, like my code below, but I’d rather like the SQL-server to do the counting:

public static Double countSaldoForEmployee(Employee e) {
    // Get all Events for the employee
    List<Event> events = Event.find("byEmployee", e).fetch();
    Double sum = 0.0    ;
    for(Event event: events) {
        if(event.totalAmount != null) {
            sum += event.totalAmount;
        }
    }
    return sum;
}

Answer 1

You should be able to do this with a simple native query. Something like the following.

public static Double countSaldoForEmployee(Employee e) {

    return  (Double)em.createNativeQuery("SELECT SUM(e.totalAmount) FROM events e where e.employee_id = "+e.id).getSingleResult();    
}