I think this is a good call for a "best practices" for mortals on JPA. :)
On Tue, 2 May 2006, Gordon Yorke wrote:
> Hello,
> We are going to need more detail. What is the cascade settings on the relationships from Reservation to User and Asset? Are they Cascade PERSIST or cascade ALL? These pre-existing User and Asset objects are they managed entities or detached entities? Can you provide the code that is performing this operation? Are there unique constraints on the database tables?
> --Gordon
>
> -----Original Message-----
> From: Marina.Vatkina_at_Sun.COM [mailto:Marina.Vatkina_at_Sun.COM]On Behalf Of
> Marina Vatkina
> Sent: Tuesday, May 02, 2006 12:44 PM
> To: users_at_glassfish.dev.java.net; persistence
> Subject: Re: select after insert issue
>
>
> Hi Davy,
>
> CC-ing persistence alias.
> Is it a Java SE or a Java EE application? Do you navigate to the related
> objects via getters?
>
> thanks,
> -marina
>
> Davy De Durpel wrote:
>> Hi,
>>
>> I have a strange behavior and I have it on build 42 and 46 (the only 2 I
>> tested).
>>
>> The problem in short is that when I do a persist of a new entity and
>> then I do a select to retrieve all entities from the database, then all
>> referenced objects are empty (all properties are Null). No way to get
>> them back then restarting the application. In all other situations
>> (selects, updates) I don't have the problem but things go wrong as soon
>> as I persist a new Entity to the database.
>>
>> I will try to explain in more detail.
>>
>> I have a table 'Reservation' that contains a link to a table 'Asset' and
>> a table 'User'.
>> I execute this query to get all the reservations for a certain user:
>> 'SELECT c FROM Reservation c WHERE c.user = :user'
>> Everything is left by default so it should be using eager fetching. The
>> result is correct and also the User and Asset information is retrieved
>> from the database.
>> I now create a new Reservation with some default values. I also add an
>> existing Asset and User object (detached from the entity manager).
>> I use em.persist to save the reservation in the database and I can
>> clearly see that this is done in a correct way.
>> I then execute the same query again to retrieve all Reservations for the
>> current user from the database but now my 'User' and 'Asset' objects
>> have all fields initialized to Null values.
>>
>> I also tried it with other Entity beans and I have the same behavior.
>>
>> Any idea what could be causing this behavior or do I need to provide
>> more details?
>>
>> Byeee...
>>
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Joseph B. Ottinger
http://enigmastation.com
Editor,
http://www.TheServerSide.com joeo@enigmastation.com