Not sure why the datastore needs to know that a Car is associated with a
particular User.
There is no easy way for the datastore to handle cascading deletes in a
M-to-M relationship w/o reference counting.
Also setting the Fetch policy to load children with the parent load is not
an option due to them being in separate entity groups.
Regardless, you can use
*getObjectById<http://db.apache.org/jdo/api23/apidocs/javax/jdo/PersistenceManager.html#getObjectById%28java.lang.Class,%20java.lang.Object%29>
*(java.lang.Class<T> cls, java.lang.Object key)
to verify the Key is referencing a particular class and an object exists.
On Wed, Oct 6, 2010 at 2:15 PM, hadf <hadrien.for...@gmail.com> wrote:
> Hello,
>
> I read that many to many relation ship must resolved by using sets of
> Key.
> But what I don't understand is how do I specify the type the Key is
> referencing.
> I mean that if I have a many to many relation ship between Car and
> User, how jpa or jdo knows that Car is associated to User ?
>
> public class Car {
> @OneToMany
> private Set<Key> users; //this relation ship is untyped
> }
>
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