Hi Noah,
Likely not ideal, but you could change your model to use a List
with OrderColumn and when adding a favorite desert you'll have to
check the List if it already exists.
Cheers,
Guy
On 07/06/2012 10:36 AM, Noah White wrote:
On Jun 7, 2012, at 7:45 AM, Guy Pelletier wrote:
Hi
Noah,
Yes, the use of an OrderColumn is currently intended to be
used with a List only. You can however use the JPA OrderBy
annotation instead which can be used with a Set.
Cheers,
Guy
Hi Guy,
Thanks for your feedback. The rub with the @OrderBy approach
is it relies on a column in the related entity, however, I
want/need to enforce an ordering on the the relationship. Some
pseudo code to illustrate:
public class Diner {
@ManyToMany
@JoinTable(...)
Set<Dessert>
favoriteDesserts;
get/set
favoriteDesserts
}
public class Dessert {
@ManyToMany(mappedBy="favoriteDesserts")
Set<Diner>
favoritedBy;
}
I want to preserve the order that a Dessert is added to the
favoriteDesserts. I also want to enforce that the Set of
favorite desserts does not contain duplicates. There is no
particular property of Dessert to indicate an favorited order
since the favorited order should be part of the join table as it
relates to that and is not unique to an instance of Dessert
which is why @OrderBy isn't really going to help.
-Noah
On 06/06/2012 5:52 PM,
Noah White wrote:
I was reading over the docs [1] regarding
Eclipselink's support for @OrderColumn. It looks like
this only applies to List and not Set. The reason I ask
is because I have a ManyToMany bi-directional
relationship (using a join table) which is a Set and is
implemented with a HashSet because the collection can't
have duplicates.
I wanted to order the entries in this set using
@OrderColumn, but it appears I can only apply this to
List, however using List will break my unique
requirement. Is this understanding correct?
If so what is the recommended strategy for this case?
Thanks,
-Noah
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