Hi Bernd,
Längerich, Bernd wrote:
Hi,
I am trying to find some information regarding metadata merging in
the following scenario:
We have a base application with some classes, db tables and a
repository_user.xml that describes the mapping. Lets say we have a
base class BasePersistentClassA and some classes that are based which
are included as extent classes in the xml file. This application is
running.
No we develop an optional plugin with a class PluginPersistentClassB
that is based on BasePersistentClassA of the application. I can now
write an additional repository.xml and merge it with:
MetadataManager mm = MetadataManager.getInstance();
DescriptorRepository dr =
mm.readDescriptorRepository("my/additional/plugin_repository.xml");
mm.mergeDescriptorRepository(dr);
However I am failing to get the correct contents regarding the
extent-class definitions of the base class. I tried to include the
following to plugin_repository.xml:
<class-descriptor class="BasePersistentClassA " <extent-class
class-ref="PluginPersistentClassB"/> </class-descriptor>
<class-descriptor class="PluginPersistentClassB " table="MyTable" ...
</class-descriptor>
Since ClassB is an "extent" of ClassA the merge of the repositories
isn't enough. The merge method is intended to merge/add new classes
without dependencies to already registered classes.
You could try to use the ClassDescriptor.addExtent(...) method to
register a new "extent":
MetadataManager mm = MetadataManager.getInstance();
DescriptorRepository dr =
mm.readDescriptorRepository("my/additional/plugin_repository.xml");
mm.mergeDescriptorRepository(dr);
//then lookup the repository
DescriptorRepository repo = mm.getRepository();
// lookup the CLD of ClassA
ClassDescriptor cldA = repo.getDescriptorFor(ClassA.class);
// add the new extent
cldA.addExtent(ClassB);
I never tried this ;-)
regards,
Armin
Something is strange, as the following code fragment does not delete
anything at the first broker.deleteByQuery() and fails at the second
one:
Criteria crit = new Criteria();
crit.addNotEqualTo("ojbConcreteClass",BaseApplicationClassX.class.getName());
Query q = QueryFactory.newQuery(Transaction.class,crit);
broker.deleteByQuery(q);
// SELECT DISTINCT ACC_TAID FROM ACC_TA ReportQueryByCriteria
subquery = new ReportQueryByCriteria(BasePersistentClassA
.class,null); subquery.setAttributes(new String[] { "id" });
subquery.setDistinct(true);
Criteria crit = new Criteria(); crit.addNotIn("externalID",subquery);
Query q = QueryFactory.newQuery(Another.class,crit);
broker.deleteByQuery(q);
It seems that the extent definitions from dr are not merged and even
corrupt the existing definitions of the application, as trying to
access all classes from the database results in an
NullPointerException:
2007.07.26 17:40:33,375
[0/ServiceRequestDispatcher-P=3/T=7-running:1/1/1] INFO cleardb:
start java.lang.NullPointerException at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement$TableAlias.hashCode(Unknown
Source) at java.util.HashMap.hash(Unknown Source) at
java.util.HashMap.put(Unknown Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.splitCriteria(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.<init>(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlSelectStatement.<init>(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.getSubQuerySQL(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendSubQuery(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendParameter(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendInCriteria(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendCriteria(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendSQLClause(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.asSQLStatement(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendClause(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendWhereClause(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlDeleteByQuery.buildStatement(Unknown
Source) at
org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.getStatement(Unknown
Source) at
org.apache.ojb.broker.accesslayer.JdbcAccessImpl.executeDelete(Unknown
Source) at
org.apache.ojb.broker.core.PersistenceBrokerImpl.deleteByQuery(Unknown
Source) at
org.apache.ojb.broker.core.PersistenceBrokerImpl.deleteByQuery(Unknown
Source) at
org.apache.ojb.broker.core.DelegatingPersistenceBroker.deleteByQuery(Unknown
Source) at
org.apache.ojb.broker.core.DelegatingPersistenceBroker.deleteByQuery(Unknown
Source) [...]
If I include the table="" part, I get the NullPointerException at:
so it seems that the existing class definition is not merged with the
additional data but overwritten.
Ommiting the extent-class-definitions from the additional xml file, I
can access all classes of the base application, but not of the
plugin. As we have several plugins, we dont want any dependencies
from the base application to the plugins.
Any hints are appreciated.
Best regards
Bernd
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