You are viewing a plain text version of this content. The canonical link for it is here.
Posted to ojb-user@db.apache.org by "Bates, Alex" <AB...@teradata-ncr.com> on 2003/07/11 02:22:56 UTC
1:N association - truncating list to 1 when query
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.
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; ..
}
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>
</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
org.apache.ojb.broker.query.Criteria@34cdfc
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:
org.apache.ojb.broker.util.pooling.ByPassConnection@1be3d02
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:
org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a
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:
org.apache.ojb.broker.util.pooling.ByPassConnection@17366cb
2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.J2EETransactionImpl]
Commit transaction org.apache.ojb.odmg.J2EETransactionImpl@f6af3b, commit on
broker org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a
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
org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a on tx
org.apache.ojb.odmg.J2EETransactionImpl@f6af3b
2003-07-10 17:18:16,379 DEBUG
[org.apache.ojb.broker.singlevm.PersistenceBrokerImpl] PB.close was called:
org.apache.ojb.broker.singlevm.PersistenceBrokerImpl@1d16ecf
2003-07-10 17:18:16,379 INFO [STDOUT] vector of resultsets:1
---------------------------------------------------------------------
To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
For additional commands, e-mail: ojb-user-help@db.apache.org
Re: 1:N association - truncating list to 1 when query
Posted by Thomas Mahler <th...@web.de>.
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
> org.apache.ojb.broker.query.Criteria@34cdfc
> 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:
> org.apache.ojb.broker.util.pooling.ByPassConnection@1be3d02
> 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:
> org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a
> 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:
> org.apache.ojb.broker.util.pooling.ByPassConnection@17366cb
> 2003-07-10 17:18:16,379 DEBUG [org.apache.ojb.odmg.J2EETransactionImpl]
> Commit transaction org.apache.ojb.odmg.J2EETransactionImpl@f6af3b, commit on
> broker org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a
> 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
> org.apache.ojb.broker.singlevm.PoolablePersistenceBroker@1de530a on tx
> org.apache.ojb.odmg.J2EETransactionImpl@f6af3b
> 2003-07-10 17:18:16,379 DEBUG
> [org.apache.ojb.broker.singlevm.PersistenceBrokerImpl] PB.close was called:
> org.apache.ojb.broker.singlevm.PersistenceBrokerImpl@1d16ecf
> 2003-07-10 17:18:16,379 INFO [STDOUT] vector of resultsets:1
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
For additional commands, e-mail: ojb-user-help@db.apache.org