Thank you for your explanation.
Well, from OOP perspective my case is perfectly valid since MyProduct
inherits most of UserProduct properties, but can be deleted, unlike
UserProduct which just changes it's status. My app dictates these rules.
Looks like this is another case when JPA dictates mapping rules rather than
being a flexible tool which adapts to application needs. Disappointing. I
think JPA needs cascading attribute for inheritance cases so that developer
can choose what to delete and what not.
And BTW why it throws optimistic violation exception instead of just
gracefully deleting everything, parent and child?
Simone Gianni wrote:
>
> Hi Paul,
> I think you are misusing the JOINED feature. When you map a hierarchy
> using JOINED you are simply telling JPA that it should persist
> additional fields in different tables. This does not mean that they are
> separate entities or that it's possible to transform one entity to
> another class. Even if JPA is saving on more than one table, that is a
> single and unique entity, and cannot be considered like two different
> entities (a parent and a child one), so persist or delete one and not
> the other.
>
> The only way I can think of is creating a new UserProduct entity,
> transfer data from the MyProduct instance to the new one, delete the
> MyProduct instance, then persist the new one preserving the id, but this
> could cause a number of problems if other bean are referencing this
> entity assuming it is a MyProduct.
>
> Probably, if you need to use MyProduct and UserProduct as separate
> entity, you should not have one extend the other, but have two distinct
> entities connected one to the other using a @OneToOne. For example :
>
> public class UserProduct {
> @OneToOne
> private MyOptionalData mydata;
>
> }
>
> public class MyOptionalData {
> @OneToOne
> private UserProduct product;
> }
>
> Hope it helps,
> Simone
>
> [email protected] wrote:
>> I have a class defined as
>> @Entity
>> @Table(name = "user_product")
>> @Inheritance(strategy = InheritanceType.JOINED)
>> public class UserProduct implements Serializable {
>> private Integer productid;
>> }
>>
>> then I have a child class defined as
>> @Entity
>> @PrimaryKeyJoinColumn(name = "id", referencedColumnName = "productid")
>> public class MyProduct extends UserProduct implements Serializable {
>> private Integer id;
>> }
>>
>> How do I delete MyProduct without deleting its parent? The parent
>> needs to be just updated, but not deleted.
>> When I try to set a value and merge UserProduct, and then delete
>> MyProduct I get "An optimistic lock violation was detected when
>> flushing object instance...".
>>
>> Help is very much appreciated.
>
>
> --
> Simone Gianni CEO Semeru s.r.l. Apache Committer
> http://www.simonegianni.it/
>
>
>
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