might be worth checking this out - from the wonder blog :-)

ERXEOControlUtilities. validateUniquenessOf provides a utility method
for validating unique EO attribute values.



2009/3/25 Dan Grec <[email protected]>:
> Full of questions today....
> I have an EO that has a field "RemoteSystemID" that must be unique in the
> DB.
> I have the constraint in the DB and that works well.
> What I would like, is a way in EOF to detect non-uniqueness without going to
> the db and relying on the SQL Exception.
> Currently, I have something like this:
>    �...@override
>     public void validateForSave() throws NSValidation.ValidationException {
>         validateRemoteSystemId();
>         super.validateForSave();
>     }
>     //check that no Categories have this same remoteSystemID
>     public void validateRemoteSystemId() {
>         NSArray<Category> categories =
> SCEOFetcher.objectsMatchingKeyAndValue(editingContext(), Category.class,
> _Category.REMOTE_SYSTEM_ID_KEY, remoteSystemId(), EOFetcher.DBEC);
>         if (categories.count() > 1)
>         throw new NSValidation.ValidationException("Category Remote System
> Id must be unique.", this, REMOTE_SYSTEM_ID_KEY);
>     }
> This works really well if there is already one in the DB with a value of say
> "123" and I try to add with with a value of "123".
> This does not work if I try to add two at the same time with a value of
> "567", it allows them both through.
> Does anyone have a strategy to catch uniqueness at the EOF level?
> Or, is it fine to just rely on the DB throwing an SQLException and catch
> that after ec().saveChanges() ?
> (I feel like letting that happen is bad, and might leave EOF in an un-happy
> state - is there any chance of that?)
> Thanks again,
> -Dan Grec
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