Hello,

I have a question about fetch sql collection. For my domain model, I have a Event, which has a Set of Market; Market has a Set of order. Can I get all these Sets by fetch sql? We know that using
"from Event event left join fetch event.markets where eventId=?" can give us the Event with initialized Set of markets. Can we get a Set of order from each market within fetched event.markets Set? I know for join fetch we can just get one collection, but here I need to get deeper collection within the objects graph.

Any help is appreciated.

Min

No, you will have to execute another query (many queries, in fact). This might be unfortunate if you have not many Markets and Orders, but keeping the outer-join fetched resultset small is a good choice as soon as you have more than a few rows (say, more than 500 in each table).

Hi Christian,

Thanks for reply. So if Event has other Sets like Ticket, then we need to provide another method as Event e1 = getEventWithTickets(eventId) in the DAO along with Event e2 = getEventWithMarkets(eventId) to initialize different Set. Can we merge these two events e1, e2 so one of them have all the Set initialized by like e2.setTickets(e1.getTickets())?

Another question is about the data structure returned to web tier. If the objects graph is complex, is it a good idea to provide another POJO to contain these relations? For example, Event has Set of Markets (which is loaded by join fetch), each Market has a Set of Orders, what is a good way to model this data structure so web tier can display it directly? Have you had this kind of situation before?

Thanks.

Min