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Re: [eclipselink-users] two instances of same object in an indirectList ?

In EclipseLink Collection will default to IndirectList when reading from the
database if the relationship is LAZY.  If it is EAGER it will default to
Vector.  If it were of type Set, it would default to IndirectSet or HashSet.

My guess as to what you are seeing is that in the container each transaction
is a new persistence context, so you get a new clone in each transaction
that has the IndirectList.  Outside the container the persistence context is
extended as long as the EntityManager exists, so when you do a find() you
get the same object that you originally persisted, and I assume your
constructor is setting it to a HashSet.  If you create a new EntityManager
or refresh() the object outside the container you will get the IndirectList.

As to why you have duplicates, this is odd, it means you have duplicate rows
in your database, or you added the object to the collection twice, which is
not good.  You should not add the object to the collection if it is already
contained in it.

Phillip Ross-3 wrote:
> HI Tom, thanks for the response.  I can certainly attempt to post the
> definition.
> On one side of the relationship the entity has two properties as follows:
> @ManyToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
>  private Department department;
> @ManyToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
> private OpeningStatus status;
> While on the other side, the properties are as follows:
> @OneToMany(mappedBy = "department",
> cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
> private Collection<Opening> openings;
> and
> @OneToMany(mappedBy = "status",
> cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})
> private Collection<Opening> openings;
> I've worked around the issue for now by redefining all of the Collection
> based properties as Set based instead.  Luckily they all fit within the
> Set semantics so I'm happy to leave them that way.  But I'm still
> wondering why the underlying Lists contain duplicates, or... are lists at
> all rather than sets.  I should mention again that the query involves
> invoking find() on an entity manager with either a Department or
> OpeningStatus and both of those have Collection based relational
> properties mapped to OpeningStatus and Department.  But the underlying
> Collection is an IndirectList (when running inside the container) and a
> HashSet when running outside.
> Thanks
> - Phillip
> ----- Original Message ----
>> From: Tom Ware <tom.ware@xxxxxxxxxx>
>> To: EclipseLink User Discussions <eclipselink-users@xxxxxxxxxxx>
>> Sent: Tuesday, January 6, 2009 9:30:03 AM
>> Subject: Re: [eclipselink-users] two instances of same object in an
>> indirectList ?
>> Hi Phillip,
>>   I am a bit surprised that you are getting a TransparentList.  I would
>> expect a 
>> TransparentSet.  Can you post the definition of the relationship?
>> -Tom
>> Phillip Ross wrote:
>> > Hi all... I'm looking for some quick ideas.
>> > 
>> > Was wondering if someone could quickly think of a few things for me to
>> check 
>> out with a problem I'm having.  I have a pair of entities with OneToMany 
>> relationships to a third entity.  If I return an instance with the entity 
>> manager using find and PK id, I get an instance and the Collection
>> contains two 
>> items.  Both items are references to the same related object... exact
>> hashCodes, 
>> etc.  When I run outside the container, the Collection is a HashSet and
>> it only 
>> contains one reference to the related item due to the Set semantics which
>> works 
>> great... but inside the container the Collection is an eclipselink
>> specific 
>> IndirectList but with dups of the same item.
>> > 
>> > So, might there be something I'm doing wrong that's creating the dups
>> in the 
>> indirect list?  I have several other similar OneToMany relations to other 
>> entities and they don't exhibit the problem, but I've been racking my
>> mind 
>> trying to figure out if there is something I'm missing here to get the
>> dedup to 
>> happen on the IndirectList.  There are several things I'm sure I could
>> implement 
>> myself to work around all of this and handle deduping and such, but I'm
>> really 
>> wondering why this duplication happens in the indirect list with these
>> specific 
>> entities and not with the other three or four other similarly patterned 
>> OneToMany related entites.
>> > 
>> > Any ideas?  I'm using eclipselink 1.0.2, container is glassfish
>> v2.1-b60e 
>> (tried with earlier glassfish versions as well).
>> > 
>> > Thanks!
>> > - Phillip
>> > 

--- James Sutherland
 EclipseLink ,
Wiki: EclipseLink , TopLink 
Forums: TopLink , EclipseLink 
Book: Java Persistence 
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