[app-engine-java-groovy] One-to-Many relationship. Select objects from datastore.
- by Olexandr
Hi.
I've omitted some code(package declarations, imports, other fields)
for shortness.
I have here simple One-to-Many relation.
It worked fine till this moment.
@PersistenceCapable(identityType = IdentityType.APPLICATION,
detachable="true")
class Restaurant implements Serializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
Key id
@Persistent(mappedBy = "restaurant")
List<RestaurantAddress> addresses = new ArrayList<RestaurantAddress>()
}
//-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
@PersistenceCapable(identityType = IdentityType.APPLICATION,
detachable="true")
class RestaurantAddress implements Serializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
Key id
@Persistent
Restaurant restaurant
}
Now i need to get(select) all the Restaurants from DB:
def getRestaurantsToExport(final String dst, final int count) {
String field = restaurantExportFields[dst]
return transactionExecute() { PersistenceManager pm ->
Query q = pm.newQuery(Restaurant.class)
q.filter = "$field == null"
q.setRange(0, count)
return q.execute()
}
}
But there are on problem - query gives me 12 restaurants(as in DB) but
every Restaurant has 0 Address but in Datastore every Restaurant has
minimum 2 addresses.
Have anyone the same problem or knows the solution ?
