[eclipselink-users] Many-To-Many Remove Problem

[sonavor <jw@xxxxxxxxxxxxxx>]

I have a problem with updating a JPA entity where a many-to-many relationship
is involved.  It appears to be some sort of session caching issue but I
can't find the source of the problem

I can add items to my main entity and see that the many-to-many mapping
table updates with the results.  When I re-select the main entity and
display the values it shows all of the mapped items.  When I remove a mapped
item and re-select the entity the removed item(s) still show up in the
select query.  However, if I look at the mapping table in the database the
items did remove correctly.

My case is this -

main table:
MEDIA_CATEGORY
category_id   integer  PK
cat_description    varchar(50)

second table:
KEYWORDS
kw_id  integer PK
kw_name  varchar(50)

mapping table:
CATKWMAP
kw_id          integer  PK
category_id  integer  PK

The MEDIA_CATEGORY JPA entity class is MediaCategory.  Here are the column
to attribute mappings -

    @Column(name = "CATEGORY_ID", nullable = false)
    private Integer categoryId;

    @Column(name = "CAT_DESCRIPTION")
    private String catDescription;

    @JoinTable(name = "CATKWMAP", joinColumns = {@JoinColumn(name =
"CATEGORY_ID", referencedColumnName = "CATEGORY_ID")}, inverseJoinColumns =
{@JoinColumn(name = "KW_ID", referencedColumnName = "KW_ID")})
    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private Collection<Keywords> catKwCollection;

In my update code I just populate a MediaCategory class with the categoryId,
catDescription and a collection of keywords ( catKwCollection );

I then tell the EntityManager to merge the changes -

em.merge(mediaCategory);

After that occurs I checked the CATKWMAP table in the database and can see
that the submitted keyword-to-media_category mappings are there.  Whether
the merge occurs where keywords are added or removed the database table ends
up with the correct results.

If I add code to check the MEDIA_CATEGORY record right after the merge -

MediaCategory mcUpdated = em.merge(mc);
Collection<Keywords> kwListing = mcUpdated .getCatKwCollection();
for (Iterator it = kwListing.iterator(); it.hasNext();) {
    KwList kwl = (KwList) it.next();
    log("updateMediaCategory - keyword: " + kwl.toString());
}

The output shows keywords that match what the updated table has.

But if I go to a screen where I select the updated MediaCategory ID and have
my code re-select the record using -

MediaCategory mc = em.find(MediaCategory.class, categoryId);

...the mc.getCatKwCollection() contains all of the keywords I had prior to
the update.  In other words, if my update removed some keyword relationships
and the table shows them removed, they still exist in this selected
MediaCategory instance.

I have to stop my web application, restart it and re-select the
MediaCategory record in order to be in-sync with the database.  What is
going on here?  I tried adding a -  em.flush() after my merge but it didn't
help.

Thanks,
-sonavor






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