Jonathan Lalou's Blog

Posts Tagged ‘Hibernate’

Case

You have a couple of Hibernate DAOs, in which a huge amount of code is duplicated: begin transactions, try/catch, close transactions, etc.
You would like to factorize your code.

Fix

• Define a SessionFactory, let’s say hibernateSessionFactory, with your own settings.

  [xml]<bean id="hibernateSessionFactory"
  class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">(…)</bean>[/xml]

• Define a TransactionManager:

  [xml]<bean id="hibernateTransactionManager"
  class="org.springframework.orm.hibernate3.HibernateTransactionManager">
  <property name="sessionFactory">
  <ref local="hibernateSessionFactory" />
  </property>
  </bean>[/xml]

• Define transactions advices:

  [xml]<tx:advice id="hibTxManager" transaction-manager="hibernateTransactionManager">
  <tx:attributes>
  <tx:method name="*" propagation="NEVER" read-only="true" isolation="READ_COMMITTED" rollback-for="find*" no-rollback-for="dontFind*"/>
  </tx:attributes>
  </tx:advice>[/xml]

• name="*" –> the aspect will apply to all methods. You may filter on patterns such as find*, get*, save*, etc.
• propagation="NEVER" –> hints the propagation level. Available options are
• REQUIRED, SUPPORTS, MANDATORY,REQUIRES_NEW, NOT_SUPPORTED, NEVER, NESTED.
• isolation="READ_COMMITTED" –>
• rollback-for="find*" –> rollback all transactions following the given pattern
• no-rollback-for="dontFind*" –> exceptions for rollbacks
• Define the AOP configuration:

  [xml]<aop:config>
  <aop:pointcut id="hibOperation"
  expression="execution(* com.lalou.jonathan.dao.hibernate.Hibernate*.*(..))" />
  <aop:advisor pointcut-ref="hibOperation" advice-ref="hibTxManager" />
  </aop:config>[/xml]

Many thanks to Jean-Pierre ISOARD for his help on this subject.

Case:

You have to use an equivalent to “select for update” in Hibernate, for instance when you migrate en EJB entity to Hibernate.

Fix:

In your query, use the option LockMode.UPGRADE. For instance, you will have:

[java]sessionFactory.getCurrentSession().load(MyMappedClass.class, myPk, LockMode.UPGRADE);[/java]

Case

• let’s consider an EJB Bean AnimalBean, linked to a table JL_Animal
• let’s have a human understandable name for the Pojo, let’s say: Animal
• let an EJB entity have following finders:

[java]
* @ejb.finder
* signature = "Collection findByBirthDate(java.lang.Integer birthDate)"
* query = "SELECT OBJECT(o) FROM AnimalBean AS o WHERE o.birthDate = ?1"
*
* @ejb.finder
* signature = "Collection findByCountryAndBirthDate(java.lang.String from,java.lang.Integer birthDate)"
* query = "SELECT OBJECT(o) FROM AnimalBean AS o WHERE o.country = ?1 AND o.birthDate = ?2"[/java]

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Here is an interesting case I have encountered this morning.

Context

I must test a Hibernate implementation of a DAO, using DBUnit and its XML dataset files as a minimal database. A CRUD unit test fails, I get this trace:

Explanation

In my dataset, I had set some primary keys at 0, 1, …, 10. Owing to my Hibernate mapping, the primary keys are generated thanks to a sequence.
On another hand, with the CRUD test, the primary keys 0, 1, …, 10 are also assigned to newly created objects.

Here is the issue: there are collisions between the XML dataset file objects and the objects created with Hibernate, because obviously two objects never share the same primary key!

Very interesting case. At firt, I spotted these errors:

SQL Error: -22, SQLState: S0002

and:

java.sql.SQLException: Table not found in statement

But here is the complete stacktrace:

"2009-10-13 12:29:17,934 ERROR hbm2ddl.SchemaExport - Unsuccessful: create table MY_ORACLE_TABLE (myOracleTableId integer not null, optimisticTimestamp timestamp not null, position double, primary key (myOracleTableId))
2009-10-13 12:29:17,934 ERROR hbm2ddl.SchemaExport - Unexpected token: POSITION in statement [create table MY_ORACLE_TABLE (myOracleTableId integer not null, optimisticTimestamp timestamp not null, position]
(...)
2009-10-13 12:29:17,949 ERROR hbm2ddl.SchemaExport - Table not found: MY_ORACLE_TABLE in statement [alter table MY_ORACLE_TABLE]
2009-10-13 12:29:17,980 DEBUG util.HibernatePersistenceTestCase - ++++++++++++++ Using Pattern HibernateMyOracleTableDAOUnitTest-testFindmyOracleTableByPK_OK.xml
2009-10-13 12:29:17,996 DEBUG util.HibernatePersistenceTestCase - ++++++++++++++ Using Pattern HibernateMyOracleTableDAOUnitTest.xml
2009-10-13 12:29:17,996 DEBUG util.HibernatePersistenceTestCase - --------------- Using dataset : HibernateMyOracleTableDAOUnitTest.xml
2009-10-13 12:29:18,355 WARN util.JDBCExceptionReporter - SQL Error: -22, SQLState: S0002
2009-10-13 12:29:18,355 ERROR util.JDBCExceptionReporter - Table not found in statement [select (...) where myOracleTable0_.myOracleTableId=?]
2009-10-13 12:29:18,371 DEBUG util.HibernatePersistenceTestCase - ++++++++++++++ Using Pattern HibernateMyOracleTableDAOUnitTest-testFindmyOracleTableByPK_OK.xml
2009-10-13 12:29:18,371 DEBUG util.HibernatePersistenceTestCase - ++++++++++++++ Using Pattern HibernateMyOracleTableDAOUnitTest.xml
2009-10-13 12:29:18,387 DEBUG util.HibernatePersistenceTestCase - --------------- Using dataset : HibernateMyOracleTableDAOUnitTest.xml

org.hibernate.exception.SQLGrammarException: could not load an entity: [com.(...)myOracleTable#147]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1799)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:47)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:41)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:2730)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:365)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:346)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:123)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:161)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:87)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:862)
at org.hibernate.impl.SessionImpl.load(SessionImpl.java:781)
at org.hibernate.impl.SessionImpl.load(SessionImpl.java:774)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:301)
at $Proxy0.load(Unknown Source)
(...)HibernateMyOracleTableDAOUnitTest.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:40)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
Caused by: java.sql.SQLException: Table not found in statement [select (...) where myOracleTable0.myOracleTableId=?]
at org.hsqldb.jdbc.Util.throwError(Unknown Source)
at org.hsqldb.jdbc.jdbcPreparedStatement.(Unknown Source)
at org.hsqldb.jdbc.jdbcConnection.prepareStatement(Unknown Source)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:442)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:368)
at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:105)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1561)
at org.hibernate.loader.Loader.doQuery(Loader.java:661)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1785)
... 42 more"

I have helped you with red bold words… Can you see the issue?

Yes, indeed position is a reserved keyword in SQL! To fix this issue, you have no choice but to rename your column.

Lorsque la gestion du typage d’une base de donnees relationnelle est confiee a Java et Hibernate, il est souvent frustrant de perdre la securite induite par les enum de Java 5. Voici comment reconcilier Hibernate et les enum.

Read the rest of this entry »

Error:

java.lang.reflect.UndeclaredThrowableException at $Proxy0.createQuery(Unknown Source) at somewhere in some Hibernate DAO... at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:40) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:301) ... 26 more Caused by: java.lang.NoSuchMethodError: org.hibernate.hql.antlr.HqlBaseParser.recover(Lantlr/RecognitionException;Lantlr/collections/impl/BitSet;)V

Fix: Upgrade AntLR from version 2.7.2 to 2.7.6

Error:

javax.ejb.EJBException: EJB Exception: : org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save():

Fix: You must assign the primary-key (which is probably a composite-id) before saving the object.

Still another dumb error:

java.lang.NullPointerException at org.dbunit.dataset.DefaultTableIterator.next(DefaultTableIterator.java:59)  at org.dbunit.dataset.AbstractDataSet.getTable(AbstractDataSet.java:77)  at org.dbunit.dataset.AbstractDataSet.getTableMetaData(AbstractDataSet.java:70)  at org.dbunit.dataset.filter.SequenceTableFilter.getTableNames(SequenceTableFilter.java:94)  at org.dbunit.dataset.filter.SequenceTableFilter.iterator(SequenceTableFilter.java:110)  at org.dbunit.dataset.FilteredDataSet.createIterator(FilteredDataSet.java:74)  at org.dbunit.dataset.AbstractDataSet.iterator(AbstractDataSet.java:112)  at org.dbunit.operation.DeleteAllOperation.execute(DeleteAllOperation.java:81)

I’m laughing because I had only to check the DBUnit XML file did start with <dataset> tag… :-S