Hello Kiran,
Look at your code and find where you populate an Application entity's
appRejectMaps collection with ApplicationRejectMap entities. If you
are not doing it, the collection will always be empty (until a
refresh). Where ever you set the
ApplicationRejectMap -> Application reference, you should also set
the Application -> ApplicationRejectMap
Here is a quick example I found:
http://www.vogella.de/articles/JavaPersistenceAPI/article.html
Best Regards,
Chris
On 22/11/2010 9:33 AM, Kiran Kumar Gubbi wrote:
Hi Christopher,
Sorry to bother you again. I am still not clear, may be an example will help
me to understand or if you can mention the changes do I need to make this
bidirectional mapping to work.
Thanks,
Kiran
christopher delahunt wrote:
Sorry I was not clearer.
No, there is nothing wrong with your mappings. This is a reoccurring
problem with bidirectional relationships, as JPA does not maintain
relationships for you - the application must maintain both sides
itself. When the application sets applicationRejectMap.application =
app, it must also add the applicationRejectMap to the app's
appRejectMaps collection, otherwise each and every time you access the
appRejectMaps it will never see this change - until you the app instance
is refreshed.
Best Regards,
Chris
On 22/11/2010 9:16 AM, Kiran Kumar Gubbi wrote:
Hi Christopher,
Here is my code.
The Application is parent entity which has collection OneToMany of
ApplicationRejectMap. The entity detail given below.
@Entity
@Table( name = "APPLICATION_TBL" )
public class Application {
@Column( name = "APPLICATION_ID", nullable = false, unique = true )
private Integer id;
@OneToMany( mappedBy = "application", fetch = FetchType.LAZY )
private Set< ApplicationRejectMap > appRejectMaps;
}
The child class ApplicationRejectMap details which as ManyToOne relation
with Application as mentioned beow.
@Entity
@Table( name = "APPLICATION_REJECT_MAP_TBL" )
public class ApplicationRejectMap {
@Column( name = "REJECT_MAP_ID" )
private Integer id;
@ManyToOne
@JoinColumn( name = "REJECT_APPLICATION" )
private Application application;
}
Do you think is there any issue on this?
Thanks,
Kiran
christopher delahunt wrote:
Hello Kiran,
From the sounds of it, the OneToMany is mapped by a OneToOne back
pointer, and are maintaining relationship changes through the OneToOne
but not the OneToMany. If you set one side of a bi directional
relationship, the application must also maintain the other side as well
or the cache becomes out of synch with what is in the database until a
refresh occurs. Invalidating the objects is essentially forcing a
refresh, which causes the OneToMany to be queried from the database.
When you add/remove from a relationship, the application will also need
to add/remove from the OneToMany collection as well.
Best Regards,
Chris
On 22/11/2010 6:01 AM, Kiran Kumar Gubbi wrote:
Hi all,
I am currently trying to improve performance of our application . One
of
the
thing I wanted to use is lazy loading of oneToMany collections. But it
looks
like the data is not retrieved eventhough it is present in the
database.
The
scenario is we upload the application form through web service, it
generates
the form data and if the form is not valid it generates rejection list
in
the database. On looking for this same form on our web application the
rejection list is not retrieved from the database. I have used fetch
type
is
lazy for this collection. One thing we have noticed that after clearing
cache using the following code from the screen the rejection list start
appearing on the screen.
( ( JpaEntityManager ) getEntityManager().getDelegate()
).getServerSession(). getIdentityMapAccessor().invalidateAll();
Is there something I am missing here ?
My colleague observed even Eager fetching is not working .
Thanks,
Kiran
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