Objectify-使用get获取给定父母的孩子？

Question

I'm trying to get all the children of a given parent key. I can achieve this using the query/ancestor methods as follows:

List<Tire> list= ofy.query(Tire.class).ancestor(new    Key<Car(Car.class,carID))).list();

The problem with this is that it the query method doesn't go through the cache. How can I get the same list using get?

Thanks

Answer 1

You can do a keys-only query, then perform a get() for the keys. This still hits the datastore, but it can reduce your costs to 1 read op + 1 small op per fetch (instead of 1 read op + 1 read op per fetch).

If you use Objectify4, it does this for you automatically (see the Query.hybrid() method).