Hello Phillip,
You are overwriting through java polymorphism when what you seem to
have been intending is more along the lines of using an
AssociationOverride from JPA inheritance.
Even though the Automobile's super.category cannot be accessed from the
application, it still exists in the in the object, so there are two
distinct mappings generated; one for this.category and one for
super.category.
I am not sure why you have the AutomobileCategory category in
Automobile when it can just use the category from its parent and then
cast it to AutomobileCategory using its own overriden get/set methods
in Automobile. This will cause only 1 mapping to be created as well,
which seems more what you are intending.
Best Regards,
Chris
On 15/07/2011 7:43 AM, Phillip Ross wrote:
Yeah so after playing around with this a little more I realize that
the queried ProductCategory entities do not have the automobile
entities in their collections because the setCategory method of the
Automobile class only does the super.category assignment which will
not handle the addition of the instance to the collection on the
category side. doing super.setCategory(category) instead of
super.category = category accomplished this and now the automobile
instances do show up.
This seems as of it is only a workaround though... with the potential
to break in other ways. Hrmmmm.
On Fri, Jul 15, 2011 at 6:18 AM, Phillip Ross
<phillip.w.g.ross@xxxxxxxxx> wrote:
I guess I should also point out... the Automobile class has a
setCategory method which sets this.category but the line below has a
super.category assignment which is commented out. When this is
uncommented, the creation of the entities works... but it seems like
this should not be necessary since the category property of the
Automobile class is mapped and referencing AutomobileCategory, not
ProductCategory.
Furthermore, if the super.category assignment is uncommented you can
see that querying all ProductCategory instances will return two... of
which one is a concrete Automobile category, but is contains no
Automobiles in it's collection. Ideally it should... since querying
for all AutomobileCategories returns the same automobile category
instance which DOES have the collection populated with Automobile
instances.
I'm wondering if I'm hitting a bug or maybe just getting too fancy
with respect to mapping inheritance with JPA :)
On Fri, Jul 15, 2011 at 6:09 AM, Phillip Ross
<phillip.w.g.ross@xxxxxxxxx> wrote:
Thanks for the reply Tom. Here are the annotated property definitions
from the classes:
Product:
@JoinColumn(nullable=false)
@ManyToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
protected ProductCategory category;
ProductCategory:
@OneToMany(mappedBy = "category",
cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
private Set<Product> products;
Automobile:
@JoinColumn(nullable=false)
@ManyToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
private AutomobileCategory category;
AutomobileCategory:
@OneToMany(mappedBy = "category",
cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
private Set<Automobile> automobiles;
The following is the code that just persists some instances of the entities:
entityManager.getTransaction().begin();
AutomobileCategory automobileCategory = new
AutomobileCategory("AC_" + UUID.randomUUID().toString(), "ENAME",
"SNAME");
for (int i = 0; i < 5; i++) {
Automobile automobile = new Automobile("A_" +
UUID.randomUUID().toString(), automobileCategory, "ENAME", "SNAME");
entityManager.persist(automobile);
}
entityManager.getTransaction().commit();
And I'm attaching the log as it's probably too big to inline.
I have a full testcase that probably illustrates more of what is going
on. I'll attach those source files too.
Thanks again
- Phillip
On Thu, Jul 14, 2011 at 8:39 AM, Tom Ware <tom.ware@xxxxxxxxxx> wrote:
Hi Phillip,
Can you please post the following:
- examples of how the category fields are mapped in both Product and
Automobile
- a code snippet the shows what you are doing
- logging of the SQL produced and the full exception trace (for logging, use
persistence unit property eclipselink.logging.level=FINEST)
-Tom
Phillip Ross wrote:
Hi all, I'm having a problem with mapping inheritance and not sure if
things are acting correctly or not. Was hoping for some hints.
The scenario I'm working with is that I have two related entity
superclasses mapped with an inheritance strategy or JOINED, and there
is a ManyToOne relationship between the two. The subclass entities
subclass the superclasses and override the relationship (or at least
this is what is intended). I had first assumed that when the tables
were created, a field would be created in both the parents table and
child table... but it appears that it was only created in the parent
table. I figured that this was OK since there would be records in the
parent tables that would map related subclass instances, but when I
attempt to persist the subclass with the ManyToOne member attribute...
an exception is thrown caused by a not-null constraint violation
corresponding to the parent table's FK field. As an experiment, I
changed the child class to populate the related property field in both
the superclass and itself, but I'm assuming this won't really work out
in the future as fetching the correct records may not work either.
To put this in more concrete terms... say I have Product and
ProductCategory as superclasses. Product has a property called
category which holds a ProductCategory instance. Automobile
subclasses Product and AutomobileCategory subclasses ProductCategory.
The Automobile class defined a property named category and is defined
to be AutomobileCategory. Since persisting an Automobile and an
AutomobileCategory would create records in all four tables... shouldnt
eclipselink know that the category field in the Product table relating
to ProductCategory be used to map the Automobile instances to the
AutomobileCategory instances?
I'm hoping someone knoww if I'm trying to map a scenario that's not
supported or if there is a trick to doing this? Perhaps an
eclipselink specific trick that goes beyond the JPA spec? If it is
supported and sounds like a bug... I have a test case to submit :)
Thanks!
- Phillip
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