Question

There are database tables in mysql at the backend corresponding to these classes with Foreign Keys defined accordingly. Let me know if I need to put those relations here.

class Itinerary {
 Airport Departure;
 Airport Arrival;
 Airline flight;
}

class Airport{
 int idAirport;
 String terminal;
 City city;
}

class City{
 int idCity;
 String name;
}    

class Airline{
 int idAirline;
 String flightNumber;
}

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I use something like this: http://pastebin.com/YzYMTBg3 to build an itinerary object. This is what is puzzling me, and I don’t know what is a good way to handle this using hibernate as my ORM.

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AirSegmentBuilder segmentBuilder = new AirSegmentBuilder();
segmentBuilder.addDepartureAirport("JFK");
segmentBuilder.addArrivalAirport("SFO");

I am trying to add departure and arrival airport (objects) to my itinerary here. These objects in turn persist in database as:

Airport:

id    |    name    | terminal
1     |    JFK     |  1
2     |    SFO     |  B1

So when I need to add these airports to my itinerary, do I need to fetch the airport objects first using a query based on name?; and then attach these objects to itinerary? Once I have the itinerary object built and save it to the database using hibernate, would it be able to pick up the foreign keys correctly ?

Answer 1

Assuming you are using xml to configure your hibernate stuff.
You may write your Itinerary.hbm.xml like this to achieve your goal :

<many-to-one name="Airport" class="pkg.Airport"
                column="foregn_key1" not-null="true" fetch="join" />
<many-to-one name="Airline" class="pkg.Airline"
                column="foregn_key2" not-null="true" fetch="join" />

where Airport, Airline and Itinerary are the tables in your DB.
Hope this helps…

Note – This is just a kind of example. You may need to update your beans accordingly.