Thanks for the recommendations on this. I tried implementing the changes
you referred to, but I must be doing something wrong because I'm still
seeing the list truncated to 1 when I have multiple ResultSets mapped to the
same Query.
As you can see below, I added a foreign key field to the ResultSetVO class
called queryId (and added QueryID column to TapResultset table), and refer
to it in the referenece-descriptor.
In the TapQuery table, there is a single QueryVO with and id of 1. In the
TapResultset table, there are two ResultSetVOs, whose QueryID column has
value of 1 (pointing to the same QueryVO).
But, when I retrieve the list of ResultSetVOs, it's truncated to 1. Is
there a problem with the new mapping?
<!-- Definitions for com.teradata.tap.component.system.resultset.ResultSetVO
-->
<class-descriptor
class="com.teradata.tap.component.system.resultset.ResultSetVO"
table="TapResultset"
>
<field-descriptor
name="id"
column="ID"
jdbc-type="INTEGER"
primarykey="true"
autoincrement="true"
/>
<field-descriptor
name="label"
column="Label"
jdbc-type="VARCHAR"
/>
<field-descriptor
name="maxRows"
column="MaxRows"
jdbc-type="INTEGER"
/>
<field-descriptor
name="queryTimeoutSecs"
column="QueryTimeoutSecs"
jdbc-type="INTEGER"
/>
<field-descriptor
name="queryId"
column="QueryID"
jdbc-type="INTEGER"
/>
<reference-descriptor name="query"
class-ref="com.teradata.tap.component.system.query.QueryVO"
auto-retrieve="true"
auto-update="true">
<foreignkey field-ref="queryId" />
</reference-descriptor>
</class-descriptor>
-----Original Message-----
From: Thomas Mahler [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 10, 2003 11:13 PM
To: OJB Users List
Subject: Re: 1:N association - truncating list to 1 when query
Hi Alex,
Bates, Alex wrote:
> I have a 1:N association - but in my case, the 1 doesn't store a
> collection of the N. Instead, each of the N stores a reference the
> parent 1. I didn't see any examples of how to do this in the JUnits
> or docs.
Have a look at the Productgroup - Article examples in the testcases.
Productgroup has a collection of Atricles. Ok, you don't have this, so
just omitt the collection-descriptor.
And each Article has a reference to its productgroup using
areferencedescriptor.
So what you describe is not that special and OJB will handle it without
any problems.
please see my comments below:
> To make things more concrete, I have a QueryVO class (not to be
> confused with OJB's query classes), which has a 1:N relationship with
> ResultSetVO class. Each ResultSetVO has a single parent QueryVO
> (QueryVO is a member of ResultSetVO).
>
> --------------- Class definitions ------------------------
>
> public class ResultSetVO implements VOInterface {
> protected Object id = null;
> protected String label = null;
> protected QueryVO query = null; ..
> }
There is no foreign attribute referencing the associated QueryVO !
>
> public class QueryVO implements VOInterface {
> protected Object id;
> protected String label;
> protected String sql;
> }
>
> So, what I want to be able to do is: navigate from the CHILD (one of
> the N) to the PARENT (the 1). Notice that ResultSetVO stores a
> reference to the parent QueryVO, but QueryVO does NOT store a
> collection of child ResultSetVOs.
>
> All the examples I see in the docs and Junit that use
> inverse-foreignkey use it for the opposite: the parent has a
> collection of children (in my case, QueryVO would have a collection of
> ResultSetVOs). But my case is different: I need to define how
> ResultSetVO can reference QueryVO.
>
> Using the mapping file below, I am able to create ResultSetVOs that
> are mapped to QueryVOs, and persist them (without errors). However,
> when I try to retrieve the list of ResultSetVOs, it always truncates
> the list at 1. I found this to be true using both the low-level PB
> API, and using an ODMG OQL query.
>
> Details: I'm running the Jboss/J2EE version of OJB; using the ODMG
> API; at the bottom is the log output where the truncation occurs.
>
>
> --------------- Mapping File ------------------------
>
> <!-- Definitions for com.teradata.tap.component.system.query.QueryVO -->
> <class-descriptor
> class="com.teradata.tap.component.system.query.QueryVO"
> table="TapQuery"
> >
> <field-descriptor
> name="id"
> column="ID"
> jdbc-type="INTEGER"
> primarykey="true"
> autoincrement="true"
> />
> <field-descriptor
> name="label"
> column="Label"
> jdbc-type="VARCHAR"
> />
> <field-descriptor
> name="sql"
> column="SqlString"
> jdbc-type="VARCHAR"
> />
> </class-descriptor>
>
> <!-- Definitions for
> com.teradata.tap.component.system.resultset.ResultSetVO
> -->
> <class-descriptor
> class="com.teradata.tap.component.system.resultset.ResultSetVO"
> table="TapResultset"
> >
> <field-descriptor
> name="id"
> column="ID"
> jdbc-type="INTEGER"
> primarykey="true"
> autoincrement="true"
> />
> <field-descriptor
> name="label"
> column="Label"
> jdbc-type="VARCHAR"
> />
> <field-descriptor
> name="maxRows"
> column="MaxRows"
> jdbc-type="INTEGER"
> />
> <field-descriptor
> name="queryTimeoutSecs"
> column="QueryTimeoutSecs"
> jdbc-type="INTEGER"
> />
> <reference-descriptor name="query"
> class-ref="com.teradata.tap.component.system.query.QueryVO"
> auto-retrieve="true"
> auto-update="true">
> <foreignkey field-ref="id" />
> </reference-descriptor>
!!!
You are using ResultSetVO.id as primary key *and* as foreign key
referencing the QueryVO.
As id is unique you will end up with seeing only 1 ResultSetVO for each
QueryVO.
This is exactly the behaviour you see!
You must define and additional foreign-key attribute
ResultSetVO.queryVOId and use this field as foreignkey field-ref !
(If you do not want to have extra foreign key attributes intruding you
persistent classes you can use the anonymous fields feature. But I recommend
to start with the more easy solution mentioned above first.)
cheers,
Thomas
> </class-descriptor>
>
>
> -------------------- Detailed logging output
> --------------------------
>
> 2003-07-10 17:18:15,864 DEBUG
> [org.apache.ojb.broker.accesslayer.JdbcAccessImpl] executeQuery :
> Query from class
> com.teradata.tap.component.system.resultset.ResultSetVO where
> [EMAIL PROTECTED]
> 2003-07-10 17:18:15,879 DEBUG
> [org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl] SQL:
SELECT
> A0.MaxRows,A0.QueryTimeoutSecs,A0.Label,A0.ID FROM TapResultset A0
> 2003-07-10 17:18:16,192 DEBUG
[org.apache.ojb.broker.accesslayer.RsIterator]
> hasNext() -> true
> 2003-07-10 17:18:16,223 DEBUG
> [org.apache.ojb.broker.singlevm.PersistenceBrokerImpl] getObjectByIdentity
> com.teradata.tap.component.system.query.QueryVO{22}
> 2003-07-10 17:18:16,223 DEBUG
> [org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl] SQL:
SELECT
> SqlString,Label,ID FROM TapQuery WHERE ID = ?
> 2003-07-10 17:18:16,333 DEBUG
> [org.apache.ojb.broker.accesslayer.StatementManager] closeResources was
> called
> 2003-07-10 17:18:16,333 WARN
> [org.jboss.resource.adapter.jdbc.WrappedConnection] Closing a statement
you
> left open, please do your own housekeeping
> 2003-07-10 17:18:16,333 DEBUG
> [org.apache.ojb.broker.accesslayer.ConnectionFactoryAbstractImpl] do
> datasource lookup, name: java:TeradataDS, user: tapuser
> 2003-07-10 17:18:16,333 DEBUG
> [org.apache.ojb.broker.accesslayer.ConnectionManagerImpl] Request new
> connection from ConnectionFactory:
> [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.accesslayer.StatementManager] closeResources was
> called
> 2003-07-10 17:18:16,379 DEBUG
[org.apache.ojb.broker.accesslayer.RsIterator]
> hasNext() -> false
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.JTATxManager]
> getTransaction called
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.JTATxManager]
> getTransactionManager called
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.JTATxManager]
> getTransactionManager called
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.ObjectEnvelopeTable] PB
> is in internal tx: false broker was:
> [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.ObjectEnvelopeTable]
call
> beginTransaction() on PB instance
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.accesslayer.ConnectionFactoryAbstractImpl] do
> datasource lookup, name: java:TeradataDS, user: tapuser
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.accesslayer.ConnectionManagerImpl] Request new
> connection from ConnectionFactory:
> [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.J2EETransactionImpl]
> Commit transaction [EMAIL PROTECTED], commit
on
> broker [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.util.pooling.ByPassConnection] ** we ignore commit
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.TransactionImpl] Close
> Transaction and release current PB
> [EMAIL PROTECTED] on tx
> [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.singlevm.PersistenceBrokerImpl] PB.close was
called:
> [EMAIL PROTECTED]
> 2003-07-10 17:18:16,379 INFO [STDOUT] vector of resultsets:1
>
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