Hi,
If a class has a list property, is there any legitimate or hackish way
in app engine to get the matched elements? For example:
class ParkingLot {
String parkingLotId;
List<String> cars;
}
ParkingLot p = new ParkingLot();
p.parkingLotId = "abc";
p.cars.add("ford_john");
p.cars.add("ford_mary");
p.cars.add("honda_tim");
p.cars.add("toyota_kim");
// Find all cars in the parking lot that are fords,
// then get their owners.
Query q = "select from ParkingLot where parkingLotId = 'abc'";
query.setFilter("cars.matches(" + "'" + "ford" + "%')");
// Right now this will return all ParkingLot instances
// that matched, but instead would want the actual String
// instanced of the List object that matched:
List<String> results = q.execute();
// results[0] = "ford_john"
// results[1] = "ford_mary"
Yeah I don't know if the partial string match would work on the list
property values, and also am pretty sure we can't get back the matched
string values.
Right now I need to write out a single CarAtParkingLot entity to do
the same select:
class CarAtParkingLot {
String parkingLotId;
String carType;
String carOwner;
}
select CarAtParkingLot where parkingLotId = 'abc' and carType =
'ford';
which will require a lot more storage, if I am understanding the
storage model correctly. I have hundreds of thousands of cars at a
given parking lot. I know a list property can only hold 5000 entities
at once, and cars leaving parking lots is a performance concern, just
wondering what options we have here,
Thanks
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