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
2009/3/17 Dan <daniel.can..mail.com>
> Greets! Neat product. I'm having a newb issue which I'm hopeful someone can
> help
> with. Here is the relevant layout: I have 2 tables (PARTY and CASE) and a
> third
> lookup table which maps the many-to-many (PARTY_CASE_LINK) - since each
> party
> can belong to 0 or more cases and each case can include 1 or more parties.
>
> PARTY PARTY_CASE_LINK CASE
> ____________________ ____________________ ____________________
> id party_id id
> firm case_id foo
> foo .. bar
>
> I want to start my lookup by loading a party by criteria and being able to
> get
> to all of the cases for that party. I have the relationships onships setup
> in
> the modeler correctly (me thinks) -- since i am able to get a List<Party>
> and
> from there I can use the relationships to get List<PartyCases> via
> getPartyCases() and from there get List<Case> via getCases() -- works like
> a
> charm!
>
> I want to avoid an N+1 lookup, so I'm **attempting** to use addPrefetch to
> my
> inial PARTY lookup. That's where it croaks.
>
> I am also using FetchLimit and FetchOffset (not that I think it should
> matter,
> but in full discolsure)
>
> Expression qualifier = ExpressionFactory.matchExp(Party.FIRM_PROPERTY,
> firm);
> SelectQuery selectQuery = new SelectQuery(Party.class, qualifier);
>
> selectQuery.addOrdering(rs.getSort(), rs.isSortAscending());
> selectQuery.setFetchLimit(rs.getPageSize());
> selectQuery.setFetchOffset(rs.getStartIndex());
>
> selectQuery.addPrefetch("partyCases");
>
> paritesAttachedToFirm = (List<Party>)
> dataContext.performQuery(selectQuery);
>
> 09:46:46,558 DEBUG BeforeAfterMethodInterceptor:183 - Calling..efore
> method
> 'fillData' at LifecycleStage 'BindingAndValidation' on ActionBean
> 'JSONPartiesActionBean'
> 09:46:46,577 INFO QueryLogger:473 - --- will run 2 queries.
> 09:46:46,579 INFO QueryLogger:427 - --- transaction started.
> 09:46:46,620 INFO QueryLogger:357 - SELECT t0.middle_name, t0.last_name,
> t0.sex, t0.firm_id, t0.id, t0.official_id_type, t0.party_type_id, t0.race,
> t0.address_append_status_id, t0.dob, t0.invite_code, t0.dod, t0.first_name,
> t0.official_id FROM PARTY t0 WHERE t0.firm_id = ? ORDER BY t0.last_name
> LIMIT 25
> OFFSET 0 [bind: 1->firm_id:2] - prepared in 40 ms.
> 09:46:46,627 INFO QueryLogger:401 - === returned 25 rows. - took 48 ms.
> 09:46:46,631 INFO QueryLogger:357 - SELECT DISTINCT t0.case_id,
> t0.party_id
> FROM PARTY_CASE_LINK t0 JOIN PARTY t1 ON (t0.party_id = t1.id) WHERE
> t1.firm_id
> = ? [bind: 1->firm_id:2]
> 09:46:46,635 INFO QueryLogger:401 - === returned 110 rows. - took 8 ms.
> 09:46:46,636 INFO QueryLogger:434 - +++ transaction committed.
> java.lang.ClassCastException: org.apache.cayenne.access.ToManyList cannot
> be
> cast to org.apache.cayenne.Persistent at org.apache.cayenne.access.
> ObjectTreeResolver$DisjointProcessor.startDisjointPrefetch
> (ObjectTreeResolver.java:335)
> at
> org.apache.cayenne.query.PrefetchTreeNode.traverse(PrefetchTreeNode.java:165)
>
> What else can I tell you to help here:
>
> In the modeler I have the relationship from PARTY to PARTY_CASE_LINK called
> "partyCases" and it's "To Many" The reverse relationship is called
> "parties"
>
> Thanks for your thoughts and advise.
>
> Dan
>
>
>
>
>
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