em.persist() does not actually write object to database. The object will
be written to database when transaction commits. If you want to force
writing the object to database than call em.flush() before executing the
query.
You can get more information from the spec or perssitence tutorial
(
http://java.sun.com/javaee/5/docs/tutorial/doc/PersistenceIntro.html)
-Mitesh
Arun Gupta wrote:
> Also wanted to mention that the following code:
>
> -- cut here --
> EntityManager em = emf.createEntityManager();
> Company c = new Company("1", "AAA Co", (float)10.0,
> (float)2.0, (float)10.0, "Jun 15, 2007");
> em.persist(c);
> out.println("Persisting to the source ...");
> out.println("and now committed!");
>
> Company c2 = (Company) em.createQuery(
> "select c from Company c where c.id = :id")
> .setParameter("id", "1").getSingleResult();
> System.out.println("Query returned: " + c2);
> -- cut here --
>
> gives the following error:
>
> -- cut here --
> javax.persistence.NoResultException: getSingleResult() did not
> retrieve any entities.
> -- cut here --
> I wonder why no error was thrown during persist() ?
>
> -Arun
>
> gives the following error:
>
> Marina Vatkina wrote:
>> Sorry, I means if you want to use EntityTransaction, you need to have
>> EMF injected/lookedup.
>>
>> Do you mean you don't see the data in the table or the table being
>> created?
>>
>> To get the former, you need transactions to commit the changes, to
>> get the latter, you need to use provider-specific tools. Do you use
>> GlassFish with Toplink Essentials? If yes, and you use CLI to deploy
>> your app, you can just specify --dropandcreatetables=true on the
>> asadmin deploy. Otherwise, you'd need to set the provider-specific
>> properties in the persistence.xml file.
>>
>> HTH,
>> -marina
>>
>> Arun Gupta wrote:
>>> Cool! Changing my code to:
>>>
>>> -- cut here --
>>> @PersistenceUnit(unitName="JavaLibrary1PU")
>>> private EntityManagerFactory emf;
>>>
>>> EntityManager em = emf.createEntityManager();
>>> // em.getTransaction().begin();
>>> Company c = new Company("1", "AAA Co", (float)10.0,
>>> (float)2.0, (float)10.0, "Jun 15, 2007");
>>> em.persist(c);
>>> out.println("Persisting to the source ...");
>>> // em.getTransaction().commit();
>>> out.println("and now committed!");
>>> -- cut here --
>>>
>>> got away with that error and my web page now shows
>>>
>>> "Persisting to the source ... and now committed!"
>>>
>>> But I do not see the Table in the database URL identified in
>>> persistence.xml. What could be wrong ?
>>>
>>> -Arun
>>>
>>> Marina Vatkina wrote:
>>>
>>>> Arun,
>>>>
>>>> The exceptions are right - you can't mix and match the access
>>>> types. You need to either inject an EMF via @PersistenceUnit, and
>>>> then create an EM or use UserTransaction for the transaction
>>>> boundaries.
>>>>
>>>> regards,
>>>> -marina
>>>>
>>>> Arun Gupta wrote:
>>>>
>>>>> Ok, I figured out how to set the transaction type (manually edit
>>>>> persistence.xml). But now I'm getting:
>>>>>
>>>>> -- cut here --
>>>>> Exception Description: Cannot use an EntityTransaction while using
>>>>> JTA.
>>>>> at
>>>>> oracle.toplink.essentials.internal.ejb.cmp3.transaction.JTATransactionWrapper.getTransaction(JTATransactionWrapper.java:66)
>>>>>
>>>>> at
>>>>> oracle.toplink.essentials.internal.ejb.cmp3.EntityManagerImpl.getTransaction(EntityManagerImpl.java:340)
>>>>>
>>>>> at
>>>>> com.sun.enterprise.util.EntityManagerWrapper.getTransaction(EntityManagerWrapper.java:1094)
>>>>>
>>>>> -- cut here --
>>>>>
>>>>> Here is my code for a WebApplication:
>>>>> -- cut here --
>>>>> @PersistenceContext(unitName="JavaLibrary1PU")
>>>>> EntityManager em;
>>>>> em.getTransaction();
>>>>> Company c = new Company("1", "AAA Co", (float)10.0,
>>>>> (float)2.0, (float)10.0, "Jun 15, 2007");
>>>>> em.persist(c);
>>>>> out.println("Persisting to the source ...");
>>>>> em.getTransaction().commit();
>>>>> out.println("and now committed!");
>>>>> -- cut here --
>>>>>
>>>>> What is missing ?
>>>>>
>>>>> -Arun
>>>>>
>>>>> Arun Gupta wrote:
>>>>>
>>>>>> Here is a great error message I see when deploying an error:
>>>>>>
>>>>>> -- cut here --
>>>>>> Deploying application in domain failed; Deployment Error -- The
>>>>>> persistence-context-ref-name [sample.NewServlet/em] in module
>>>>>> [C:\Users\Arun Gupta\WebApplication5\build\web] resolves to a
>>>>>> persistence unit called [JavaLibrary1PU] which is of type
>>>>>> RESOURCE_LOCAL. Only persistence units with transaction type JTA
>>>>>> can be used as a container managed entity manager. Please verify
>>>>>> your application.
>>>>>> -- cut here --
>>>>>>
>>>>>> Little detailed but very clearly conveys what is possibly wrong
>>>>>> in the application. Now how do I fix it when generating this PU
>>>>>> in NB ?
>>>>>>
>>>>>> -Arun
>>>>>
>>>>>
>>>>>
>>>>
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>>>>
>>>
>>
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>