With Spring Roo unable to map two entities together without exception

[Rootis]

I have tired to search in this forum and everywhere with google for my problem solution, but nothing has helped, so: I'm creating very simple web application with spring roo v1.2.3. My log.roo file:

project --topLevelPackage com.test --projectName springRooJPA --java 6 --packaging JAR
jpa setup --provider HIBERNATE --database HYPERSONIC_IN_MEMORY 
entity jpa --class ~.domain.Person
field string --fieldName name
entity jpa --class ~.domain.Community
field string --fieldName title
web jsf setup --library PRIMEFACES --implementation APACHE_MYFACES --theme EGGPLANT 
web jsf all --package ~.jsf

When application starts - no exceptions are thrown and website works fine. After that I'm trying to reach some mapping between entities, so I execute this command:

field set --class ~.domain.Person --fieldName communities --type ~.domain.Community --cardinality ONE_TO_MANY --mappedBy personCommunities

I have tried many variants to reach such mapping between entities: without property --mappedBy; --carcinality MANY_TO_MANY and executed two field set commands, to both entities, but all these variants made the same exception at application startup:

[localhost-startStop-1] ERROR org.springframework.web.context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in file [C:\Java\workspaces\spring_roo_tests\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\springRooJPA\WEB-INF\classes\META-INF\spring\applicationContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: persistenceUnit] Unable to build EntityManagerFactory
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1486)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:524)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:461)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1117)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:922)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: persistenceUnit] Unable to build EntityManagerFactory
	at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:915)
	at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:890)
	at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:74)
	at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:286)
	at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:310)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1545)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1483)

All my configuration files are unchanget (generated by Spring Roo). This is persistance.xml file:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="persistenceUnit" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="create"/>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy"/>
            <property name="hibernate.connection.charSet" value="UTF-8"/>
        </properties>
    </persistence-unit>
</persistence>

So why is rising that exception when some mapping between two entities is made and how to reach such mapping successfully?

[Rootis]

So finally the problem is solved. When such exception (Error creating bean with name 'entityManagerFactory') was throwed - mapping command was wrong (it was sometimes, when I tried many different Spring Roo commands). When I made this Spring Roo command:

field set --class ~.domain.Person --fieldName communities --type ~.domain.Community --cardinality ONE_TO_MANY

starting project was throwing errors:

2013-01-09 00:15:26,755 [localhost-startStop-1] ERROR org.hibernate.tool.hbm2ddl.SchemaExport - HHH000389: Unsuccessful: alter table person_communities drop constraint FKB4F94C5D55425C65

2013-01-09 00:15:26,755 [localhost-startStop-1] ERROR org.hibernate.tool.hbm2ddl.SchemaExport - user lacks privilege or object not found: PUBLIC.PERSON_COMMUNITIES

2013-01-09 00:15:26,755 [localhost-startStop-1] ERROR org.hibernate.tool.hbm2ddl.SchemaExport - HHH000389: Unsuccessful: alter table person_communities drop constraint FKB4F94C5DC2C99695

2013-01-09 00:15:26,755 [localhost-startStop-1] ERROR org.hibernate.tool.hbm2ddl.SchemaExport - user lacks privilege or object not found: PUBLIC.PERSON_COMMUNITIES

Appears that such errors doesn't mean any problem, they shows only when --database HYPERSONIC_IN_MEMORY is used. But with these errors everything works fine (using any database). When switching to real database (MySQL or Postgresql) such errors doesn't show.

[MiB]

field set --class ~.domain.Person --fieldName communities --type ~.domain.Community --cardinality ONE_TO_MANY --mappedBy personCommunities

So why is rising that exception when some mapping between two entities is made and how to reach such mapping successfully?

You also need to link back the MANY class to the ONE class with

field reference --class ~.domain.Community --fieldName person --type ~.domain.Person --cardinality MANY_TO_ONE

in order for the JPA relationship to be complete.