mapping problem with polymorphism

wykoff · **Posted:** Mon Aug 28, 2006 7:08 am

Hi,

I have one class (CI) which has 2 many-to-many associations. The associations are with 2 subclasses (Factor, Status) of an abstract class (Definition). The Definition hierarchy is mapped TABLE_PER_CLASS.

On the CI-side, it seemed pretty easy, I just declare the 2 collections:

Code:

@Entity
@Table(name="CIS")
public class CI extends Id {
    private Collection<Status> statuses;
    private Collection<Factor> factors;

    @ManyToMany    
    @JoinTable(name="CI_STATUS",
        joinColumns = { @JoinColumn( name="CI_ID", referencedColumnName = "Id", nullable=false) },
        inverseJoinColumns = {@JoinColumn( name="STATUS_ID", referencedColumnName = "Id", nullable=false)})
     public Collection<Status> getStatuses() {
        return statuses;
    }

    @ManyToMany    
    @JoinTable(name="CI_FACTOR",
        joinColumns = { @JoinColumn( name="CI_ID", referencedColumnName = "Id", nullable=false) },
        inverseJoinColumns = {@JoinColumn( name="FACTOR_ID", referencedColumnName = "Id", nullable=false)})
    public Collection<Factor> getFactors() {
        return factors;
    }
}

But then I have problems on the other side. I can't put the collection of CIs
in the parent class because I have to specify the other end of the
relationship, but this depends on the subclass. So I thought I would try
putting a collection of CIs in each subclass:

Code:

@Entity
public class Factor extends Definition {
    private Collection<CI> cis;
    @ManyToMany( mappedBy="factors" )
    public Collection<CI> getCis() {
        return cis;
    }
}

Code:

@Entity
public class Status extends Definition {
    private Collection<CI> cis;
    @ManyToMany( mappedBy="statuses" )
    public Collection<CI> getCis() {
        return cis;
    }
}

Code:

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class Definition extends BaseObject {
    
    public abstract Collection<CI> getCis();
}

But I get the exception message listed below. I then tried moving the
collection of cis to the parent class:

Code:

@Entity
public class Factor extends Definition {

    @ManyToMany( mappedBy="factors" )
    public Collection<CI> getCis() {
        return cis;
    }
}

Code:

@Entity
public class Status extends Definition {

    @ManyToMany( mappedBy="statuses" )
    public Collection<CI> getCis() {
        return cis;
    }
}

Code:

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class Definition extends BaseObject {
    protected Collection<CI> cis;
    public abstract Collection<CI> getCis();
}

But I still get the same error. Does anyone know if what I'm trying to do is legal? It seems like it should be possible.

Here is my hibernate context:

Code:

   <bean id="transactionManager"
      class="org.springframework.orm.hibernate3.HibernateTransactionManager">
      <property name="dataSource">
         <ref bean="dataSource" />
      </property>
      <property name="sessionFactory">
         <ref local="sessionFactory" />
      </property>
   </bean>
   
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
      <property name="dataSource">
         <ref bean="dataSource" />
      </property>
      <property name="hibernateProperties">
         <props>
            <prop key="hibernate.dialect">
               org.hibernate.dialect.OracleDialect
            </prop>
         </props>
      </property>

     <property name="annotatedClasses">
        <list>
         <value>com.hp.ov.shm.ce.bo.BaseObject</value>   
         <value>com.hp.ov.shm.ce.bo.Definition</value>
         <value>com.hp.ov.shm.ce.bo.Factor</value>
         <value>com.hp.ov.shm.ce.bo.Status</value>
         <value>com.hp.ov.shm.ce.bo.CI</value>

         </list>
     </property>
  

Exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager' defined in class path resource [hibernateObjects.xml]: Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [hibernateObjects.xml]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: java.util.Collection, for columns: [org.hibernate.mapping.Column(cis)]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [hibernateObjects.xml]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: java.util.Collection, for columns: [org.hibernate.mapping.Column(cis)]
Caused by: org.hibernate.MappingException: Could not determine type for: java.util.Collection, for columns: [org.hibernate.mapping.Column(cis)]
at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:266)
at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:253)
at org.hibernate.mapping.Property.isValid(Property.java:185)
at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:395)
at org.hibernate.mapping.RootClass.validate(RootClass.java:192)
at org.hibernate.cfg.Configuration.validate(Configuration.java:1021)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1206)
at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:871)
at org.springframework.orm.hibernate3.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:797)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:901)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:870)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:393)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:257)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:168)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:226)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:115)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:798)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:589)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:389)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:257)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:168)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:254)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:332)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:92)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:77)
at org.springframework.test.AbstractSpringContextTests.loadContextLocations(AbstractSpringContextTests.java:130)
at org.springframework.test.AbstractDependencyInjectionSpringContextTests.loadContextLocations(AbstractDependencyInjectionSpringContextTests.java:224)
at org.springframework.test.AbstractSpringContextTests.getContext(AbstractSpringContextTests.java:110)
at org.springframework.test.AbstractDependencyInjectionSpringContextTests.setUp(AbstractDependencyInjectionSpringContextTests.java:192)
at junit.framework.TestCase.runBare(TestCase.java:128)
at org.springframework.test.ConditionalTestCase.runBare(ConditionalTestCase.java:69)
at junit.framework.TestResult$1.protect(TestResult.java:110)
at junit.framework.TestResult.runProtected(TestResult.java:128)
at junit.framework.TestResult.run(TestResult.java:113)
at junit.framework.TestCase.run(TestCase.java:120)
at junit.framework.TestSuite.runTest(TestSuite.java:228)
at junit.framework.TestSuite.run(TestSuite.java:223)
at org.junit.internal.runners.OldTestClassRunner.run(OldTestClassRunner.java:35)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)

[/code]

damnhandy · **Posted:** Mon Aug 28, 2006 7:26 am

I'll assume that your BaseObject defines the objects identifer. Second, you're using InheritanceType.TABLE_PER_CLASS, which is a union-subclass and will perform a union of the tables involved. Since this subclass type is usually reserved for the rarest of cases, I'd double check that this is indeed the strategy you want to be using. My hunch is that you are looking to use InheritanceType.JOINED or prehaps even InheritanceType.SINGLE_TABLE. If InheritanceType.TABLE_PER_CLASS is correct, you most likely will need to defined the @Table that the sub class is bound to. Otherwise, Hibernate will try yo guess the name of the table based on the class name.

Ryan-

wykoff · **Posted:** Mon Aug 28, 2006 7:59 am

I've pretty much figured out what is causing my problem: I have the getCis() method in the base class. Apparently, Hibernate interprets any method with the format get<whatever> as being a persistent attribute. Since my method is abstract, it can't figure it out.

So, renamed the abstract method in the base class, and then in the child classes, I just call the attribute accessor for cis.

Anyone know how to make Hibernate ignore certain get methods?

ps: sorry, ryan, but your reply didn't help me much. The table_per_class is what I wanted, and yes, the BaseObject is a mapped superclass which has an id. But thanks for replying anyway!

damnhandy · **Posted:** Thu Aug 31, 2006 4:31 pm

You can mark the getters you want Hibernate to ignore with an @Transient annotation.

Ryan-

wykoff · **Posted:** Fri Sep 22, 2006 11:47 am

Ryan,

That was the solution to my problem, but I figured it on my own. I still gave you "yes" though. I was afraid that the @Transient would make Hibernate ignore my property entirely, but it didn't happen. I was able to override the methods in my child classes and annotate them and all is well.