I'd recommend basing your code on the example here to get something working:
http://gae-java-persistence.blogspot.com/2009/10/creating-bidrectional-owned-one-to-many.html
Then you can start tweaking.
Max
On Wed, Dec 30, 2009 at 3:02 PM, markm208 <markm...@gmail.com> wrote:
> I am thoroughly confused… I am trying to set up a simple one to many
> relationship using JPA, I think that this should work but instead I
> get the error "Primary key for object of type Member is null." Any
> help would be greatly appreciated.
>
> @Entity(name = "Member")
> public class Member
> {
> @Id
> @GeneratedValue(strategy = GenerationType.IDENTITY)
> private Key id;
>
> @Basic //datastore specific type
> private Email memberEmail;
> private String memberPassword;
> private String memberFirstName;
> private String memberLastName;
> @Basic //blob of text not searchable
> private Text memberDescription;
>
> //Member 'owns' the Searches
> @OneToMany(mappedBy = "memberWhoCreated", cascade=CascadeType.ALL)
> private List < Search > searches = new ArrayList < Search >();
>
> //getters and setters
> //...
> }
>
> @Entity(name = "Search")
> public class Search
> {
> @Id
> @GeneratedValue(strategy = GenerationType.IDENTITY)
> private Key id;
>
> private List < String > searchStrings;
> private boolean allowOthersToSee;
> @Basic //datastore specific type
> private Text contextOfSearch;
>
> @ManyToOne(fetch = FetchType.LAZY)
> private Member memberWhoCreated;
>
> public static Search createASearch(boolean allowOthersToSee, String
> context, Member member)
> {
> Search search = null;
>
> EntityManager em = null;
> try
> {
> //get the entity manager
> em = EMF.get().createEntityManager();
>
> //create the search from the form variables
> search = new Search();
> search.setAllowOthersToSee(allowOthersToSee);
> search.setContextOfSearch(new Text(context));
> search.setMemberWhoCreated(member);
>
> em.getTransaction().begin();
> try
> {
>
> //store the member
> em.persist(search);
> em.getTransaction().commit();
> }
> finally
> {
> if (em.getTransaction().isActive())
> {
> em.getTransaction().rollback();
> }
> }
> }
> finally
> {
> em.close();
> }
>
> return search;
> }
>
> //getters and setters
> //...
> }
>
> --
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