Hm.
Never tried it, but, could you define two /obj/ relationships?
One flattened and one not?
Robert
On Mar 17, 2009, at 3/174:16 PM , Mike Kienenberger wrote:
Yes, but as far as I know, Dan cannot flatten the relationship list
without losing access to the other information contained in the join
table.
I have had the same issue, and as far as I know, you have to live
without flattened relationships in this case.
On Tue, Mar 17, 2009 at 2:34 PM, Andrey Razumovsky
<[email protected]> wrote:
Dan,
As far as I know, Cayenne *should* allow that prefetch and there
should be
less than N+1 select. Is there any exception now? You'd likely want
to check
prefetch docs [1] to see that your query isn't under limitation
described
there.
About flattened relationships, these ones only affect object layer,
not
database layer. So all DB structure will remain untouched. Have a
look at
many-to-many modeling article [2]! It's a bit out of date
(ObjRelationship
mapping dialog has changed recently and became more user-friendly),
but
you'll get the point!
Andrey
[1] http://cayenne.apache.org/doc/prefetching.html
[2] http://cayenne.apache.org/doc/many-to-many-relationships.html
2009/3/17 Dan <[email protected]>
Andrey Razumovsky <razumovsky.andrey <at> gmail.com> writes:
Hi Dan!
It seems quite strange to me that relationship from
PARTY_CASE_LINK to
PARTY
is called "parties". So seems it's to-many. But PARTY_CASE_LINK has
"partyid", so no more than one PARTY can exist for PARTY_CASE_LINK.
Also can't flattened relationships [1] be useful for you in this
case?
[1] http://cayenne.apache.org/doc/flattened-relationships.html
Andrey
Andrey,
Ahh - yes - there was a flaw in the data model - the relationships
to the
PARTY_CASE_LINK table should be toMany, but all of the reverse
relationships
should be toOne.
So i now have relationships that allow me to get
List<PartyCaseLink> casesLinks = pty.getPartyCases();
for (PartyCaseLink caseLink : casesLinks)
{
CourtCase cases = caseLink.getCase();
... do stuff
}
That is now resolved, and I can get "half" way to the objects that
I want
without additional DB queries using:
selectQuery.addPrefetch("partyCases");
BUT -- i see that cayenne is not allowing me to addPrefetch all
the way to
the
"case" -- e.g. i want to:
selectQuery.addPrefetch("partyCases.case");
to avoid going back to the database N times (1 per row).
...
Also - flattened relationships look interesting, but since I have
a "real"
relationship in the database there already, shouldn't i be able to
use
that?
Thanks again in advance.
dan
