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Re: [eclipselink-users] OneToMany list insertion problem
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You mention you are making two requests, the first to make changes to the list,
and the second where you see the problem. Can you please give some more details
about how this is work.
How are the transactions delineated? Is the first one finished by the time the
2nd one starts?
How are you getting the EntityManagers?
Can you give some pseudo code for each request?
What version of EclipseLink are you using?
-Tom
On 28/02/2012 10:39 AM, Renee Revis wrote:
I have a bi-directional ManyToOne mapping between two entities. I maintain the
order of the list on the OneToMany side based on a ranking field. Initially I
can create the entities and everything is fine. After that, when I use a
question line, I remove it from the list, update the ranking and then add it
back into the list based on the new ranking value. I realize that the ManyToOne
side is the owning side and it's up to me to maintain the list order in memory
on the ManyToOne side, so that's what I'm trying to do.
Everything seems to work fine at first. Just before the EJB transaction
finishes, I log the elements of the list and everything is as I expect. However,
when I make the next request (i.e., a new EJB transaction), the list shows that
the element was removed from the list, but never added back in. This doesn't
match what it previously showed, however, in the first EJB transaction context.
If I do a JPA query for the elements that are actually in the database, all of
the elements are there. And if I restart the server to force everything to be
restored from the database, it all comes back as I expected (i.e., with the
element in the list and ordered as I expected), so it seems to be a caching
issue somehow with the persistence context. I can't figure out why, in the new
transaction, I would see the change from removing the element, but not from
inserting it. They both happen in the same transaction so I should see either
both changes or neither.
Does anyone have any ideas as to what might be causing this problem? I've tried
a variety of things, and nothing has worked so far.
Thanks for any help,
Renee
The relevant parts of the entities are:
public class UserSelectorQuestionLine implements Serializable {
private Integer ranking;
@ManyToOne
private UserSelectorQuestionGroup questionGroup;
}
and
public class UserSelectorQuestionGroup implements Serializable {
@OrderBy("ranking ASC")
@OneToMany(fetch=FetchType.EAGER, mappedBy="questionGroup")
private List<UserSelectorQuestionLine> questionLines;
}
And the routine I use to add an element into the list in the
UserSelectorQuestionGroup class is:
public void addUserSelectorQuestionLine(UserSelectorQuestionLine
newUserSelectorQuestionLine) {
int index=0;
Random gen = new Random();
if (this.questionLines.size() == 0) {
this.questionLines.add(newUserSelectorQuestionLine);
} else {
for (UserSelectorQuestionLine nextQuestionLine : this.questionLines) {
if (newUserSelectorQuestionLine.getRanking() < nextQuestionLine.getRanking()) {
break;
} else if
(newUserSelectorQuestionLine.getRanking().equals(nextQuestionLine.getRanking())) {
// We want to mix up the order of the question lines that have equal ranking
if (gen.nextInt(2) == 1) {
break;
}
}
index++;
}
this.questionLines.add(index, newUserSelectorQuestionLine);
}
this.minRanking = questionLines.get(0).getRanking();
}
I know this routine is called and is working correctly because I can display the
elements of the list in the log after this is called and everything is as
expected in the first EJB transaction context.
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