OneToMany from JPA/JDO to Objectify

Question

I am moving from Datanucleus to Objectify. How do I rewrite the following OneToMany code for Objectify?

@Entity
public class Person{
  …
  @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
  private Set<Dog> dogs = new HashSet<Dog>();
  …
}

Right now to query Person and get all my dogs, I simply do

public Person findById(String uid) {
  EntityManager mgr = getEntityManager();
  try {
    String jpql = "SELECT a FROM Person a WHERE a.uid = :uid";
    TypedQuery<Person> q = mgr.createQuery(jpql, Person.class);
    q.setParameter("uid", uid);
    return q.getSingleResult();
  } catch (Exception e) {// entityNotFoundException or NoResultException
    return null;
  } finally {
    mgr.close();
  }
}

And I can iterate through dogs as

Person owner = personDao.findById(id.getUid());
for (Dog dog : owner.getDogs()) {
  //… do stuff
}

By the way, uid is not annotated as @Id so that it is not a key.

Answer 1

Basically, if you want an object A to "have many" object B's you have to make A have a field that holds a list of pointers (Keys) to the Bs. This is described on the oficial Objectify's documentation [1].

[1] https://github.com/objectify/objectify/wiki/Entities#one-to-many-relationships