如何在Hibernate中按实体类的属性属性进行过滤

Question

I'm using Hibernate in Java to map classes to DB tables. I have a Person table, each entry has many Pets, each of which has many Toys.

I'd like to be able to filter these in my DAO based on attributes of the toys; for example, find all people with pets that have red toys, as a List<Person> . How can I filter on this?

Person class:

@Entity
public class Person {

    ...
    @OneToMany(mappedBy = "person")
    private List<Pet> pets;

    ...
}

Pet class:

@Entity
public class Pet {

    ...
    @OneToMany(mappedBy = "pet")
    private List<Toy> toys;

    ...
}

Toy class:

@Entity
public class Toy {

    ...
    private String colour;

    ...
}

Answer 1

I am not sure what you mean 'filter' in this case, but you can always use HQL. For example:

select p from Person p 
              inner join p.pets as pets
              inner join pets.toys as toys
              where p.pets.size() > 0 
              and toys.color = 'red'

Maybe where condition ' p.pets.size() > 0 ' is redunant here, because of inner join.