Hi Justin,
such an issue has not been reported before. Can you please create a new
issue in jira about it.
The behaviour you recognized is not intended but it may be caused by
Castor's internal design. It is expected that the resultset of a query
returns multiple records of the entity you queried (A). This will happen
if the entity (A) has a 1:n relation to another entity (B). The records
returned will not only contain columns of the entity queried (A) but
also columns of the related entities (B). While columns of the queried
entity (A) do not differ, the columns belonging to the related entity
(B) will.
To be on the save side I think we should add a default order to the
original query internally as without this order the sequence of the
records will depend on the underlaying database engine. Another option
would be to change the loading strategy and load related entities with
separate queries.
Having said that I've started to refactor Castor's database layer step
by step a while ago but as it looks at the moment this will take some
more time.
Regards
Ralf
Justin Case schrieb:
> Hello list,
>
> We noticed that Castor 1.2 is returning duplicate objects when the "IN"
> clause is used in the select query. The duplicates will be however eliminated
> with an "ORDER BY" clause on the primary key. Is this behavior "by design"?
> Because we had quite a hard time until we found the problem and its
> workaround... or do you have better suggestions than imposing this ordering?
>
> The explanation can be seen in the below Castor code snippets. The Object is
> created based on the identity variable. The identity is taken by moving
> forward in the Resultset until the first different value is found. For that
> Identity Castor is creating the Object. BUT if the Result set is not ordered
> on the primary key then the same value can come more than once to the
> identity so Castor will create the object more than one time for the same
> value. In other words, it duplicates the result.
>
> Thanks,
> J
>
> code from OQLQueryImpl.java:
>
> public boolean hasMore(final boolean skipError) throws PersistenceException
> {
> Object identity;
>
> if (_lastObject != null) {
> return true;
> }
> if (_results == null) {
> return false;
> }
> try {
> identity = _results.nextIdentity();
> while (identity != null) {
> try {
> _lastObject = _results.fetch();
> if (_lastObject != null) {
> break;
> }
> } catch (ObjectNotFoundException except) {
> // Object not found, deleted, etc. Just skip to next one.
> identity = _results.nextIdentity();
> } catch (PersistenceException except) {
> // Error occured. If not throwing exception just skip to
> // next object.
> identity = _results.nextIdentity();
> if (!skipError) {
> throw except;
> }
> }
> }
> if (identity == null) {
> _results.close();
> _results = null;
> }
> } catch (PersistenceException except) {
> _results.close();
> _results = null;
> if (!skipError) {
> throw except;
> }
> }
> return (_lastObject != null);
> }
>
> and respectively in SQLQuery.java:
>
> // We move forward in the ResultSet, until we see another
> identity or run out of rows.
> while (_rs.next()) {
> // Load identity from current row.
> currentIdentity = loadSQLIdentity();
>
> // Compare with wantedIdentity and determine if it is a new
> one.
> if (identitiesEqual(wantedIdentity, currentIdentity)) {
> // Load next row of object data from _rs into <_fields>
> array.
> loadRow(_fields, originalFieldNumber, false);
> } else {
> // We are done with all the rows for our obj. and still
> have rows left.
> _lastIdentity = currentIdentity;
>
> // As stamp is never set, this function always returns
> null ... ???
> // (Don't ask me, it was like that before I modified the
> code! :-)
> return stamp;
> }
> }
>
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe from this list, please visit:
>
> http://xircles.codehaus.org/manage_email
>
>
--
Syscon Ingenieurbüro für Meß- und Datentechnik GmbH
Ralf Joachim
Raiffeisenstraße 11
72127 Kusterdingen
Germany
Tel. +49 7071 3690 52
Mobil: +49 173 9630135
Fax +49 7071 3690 98
Internet: www.syscon.eu
E-Mail: [email protected]
Sitz der Gesellschaft: D-72127 Kusterdingen
Registereintrag: Amtsgericht Stuttgart, HRB 382295
Geschäftsleitung: Jens Joachim, Ralf Joachim
---------------------------------------------------------------------
To unsubscribe from this list, please visit:
http://xircles.codehaus.org/manage_email
