Hello,
The Google Datastore has four ways that you can store a Primary Key
ID: String, Long, and two variations on Google's own Key object. If
you want to create a parent/child relationship between two persisted
objects (in your case, evento is the parent and distritos is the
child), then you need to use Google's Key object as the primary ID.
See:
http://code.google.com/appengine/docs/java/datastore/creatinggettinganddeletingdata.html#Keys
"If the class is used as a "child" class in a relationship, the key
field must be of a type capable of representing an entity group
parent: either a Key instance, or a Key value encoded as a string."
So, you have two options:
1. Change your Long id values to Key id values.
2. Instead of storing "private distritos distrito" directly in your
evento object, store a reference to the id: "private Long distrito_id"
Jake
On Feb 6, 4:06 pm, chevelle <jvall...@vnperu.com> wrote:
> Hi
> I am new in the list, in these days i am trying save data between two
> entity beans using JPA but without success, i am cheking the log nd
> says:
>
> Uncaught exception from servlet
> javax.persistence.PersistenceException: Error in meta-data for
> beans.distritos.id: Cannot have a java.lang.Long primary key and be a
> child object (owning field is beans.evento.distrito).
>
> this is my servlet:
> Long id =
> Long.parseLong(request.getParameter("idDistrito"));
> response.setContentType("text/html");
> EntityManager cn = emf.get().createEntityManager();
>
> Query q = cn.createQuery("SELECT d FROM distritos d WHERE
> d.id = :codigo");
> q.setParameter("codigo",id);
> distritos dist = (distritos) q.getSingleResult();
>
> EntityManager cn2 = emf.get().createEntityManager();
> cn2.getTransaction().begin();
>
> evento e = new evento();
> e.setDistrito(dist);
> Date fecha = new Date();
> e.setFechaCreacion(fecha);
>
> try{
> cn2.persist(e);
> response.getWriter().write("ok");
> }finally{
> cn2.getTransaction().commit();
> cn2.close();
> }
>
> this is my entity bean
>
> Evento:
> @Entity
> public class evento implements Serializable {
> @Id
> @GeneratedValue(strategy = GenerationType.IDENTITY)
> Long id;
>
> @Temporal(javax.persistence.TemporalType.DATE)
> private Date fechaCreacion;
>
> @JoinColumn
> @OneToMany(cascade = CascadeType.ALL)
> private distritos distrito;
>
> --getter and setter--
>
> Distrito:
> @Entity
> public class distritos implements Serializable {
> @Id
> @GeneratedValue(strategy = GenerationType.IDENTITY)
> Long id;
> private String distrito;
>
> --getter and setter--
>
> i hope anyone help me, Thank!
>
> Johan
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