使用过滤器进行对象化投影查询

Question

Given the class

@Entity
public class Goat{
   Long pen;
   Long car;
   Boolean active;
   …
}

I need to create a projection query that returns a list of Long s. How should I edit the following so it works?

List<Long> cars = ofy().load().type(Goat.class).filter("pen", pen).filter("active", true).project("car").list();

Answer 1

You need to index all fields you plan to query/filter on. eg.

@Index
 Long pen;
@Index
 Long car;