org.hibernate.MappingException: Unknown entity: library.model.Person

Question

I've been struggling with this all day but haven't yet found a solution.

I have a simple entity mapping to a database table:

@Entity
@Table(name = "PERSON")
public class Person implements Serializable {

// Attributes.    
@Id
@Column(name = "ID", unique = true, nullable = false)    
@GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;

@Column(name = "NAME", nullable = false, length=50)      
private String name;

@Column(name = "ADDRESS", nullable = false, length=100)
private String address;

@Column(name = "TELEPHONE", nullable = false, length=10)
private String telephone;

@Column(name = "EMAIL", nullable = false, length=50)
private String email;

@OneToMany(cascade=CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name="PERSON_ID")   
private List<Book> books;

// Constructors.
public Person() {
    this.id = 0;
    this.name = ("");
    this.address = ("");
    this.telephone = ("");
    this.email = ("");
    this.books = null;
}

This entity is governed by a Spring controller with the following method:

@RequestMapping(value = "/register", method = RequestMethod.POST)
public String post(@ModelAttribute("person") Person person, 
                   BindingResult bindingResult, 
                   SessionStatus sessionStatus,
                   Model model /* , 
                   HttpSession session */) throws DAOException {                  
    logger.info(PersonController.class.getName() + ".post() method called.");

    personValidator.validate(person, bindingResult);
    if (bindingResult.hasErrors()) {
        return "register";
    }
    else {

        // Write Person to database.
        personService.insert(person);

        // Set view.
        sessionStatus.setComplete();             
        return "options";            
    }
} 

The service class is:

@Service("personService")
@Transactional
public class PersonService {

@Autowired 
PersonDAO personDAO;

public void insert(Person person) throws DAOException {
    personDAO.insert(person);
}

And the DAO is as follows:

@Repository("PersonDAO")
public class PersonDAOImpl implements PersonDAO {

@Autowired
private SessionFactory sessionFactory;
static final Logger logger = Logger.getLogger(PersonDAOImpl.class.getName()); 

@Override
public void insert(Person person) throws DAOException {
    logger.info(PersonDAOImpl.class.getName() + ".insert() method called.");

    Session session = sessionFactory.openSession();
    Transaction transaction = session.getTransaction();
    try {
        transaction.begin();
        session.save(person);
        transaction.commit();
    }
    catch(RuntimeException e) {
        transaction.rollback();
        throw new DAOException(e);
    }
    finally {
        session.close();
    }
}

And of course the part of my Spring servlet binding everything together:

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource"></property>        
    <property name="hibernateProperties">
        <props>
           <prop key="hibernate.dialect">org.hibernate.dialect.DerbyDialect</prop>
           <prop key="hibernate.show_sql">true</prop>
           <prop key="hibernate.current_session_context_class ">thread</prop>

           <!-- What to do with the database schema. -->
           <prop key="hbm2ddl.auto">validate</prop>    
           <!-- validate:    validate the schema, makes no changes to the database.
                update:      update the schema.
                create:      creates the schema, destroying previous data.
                create-drop: drop the schema at the end of the session. -->                 
        </props>            
    </property>                    
</bean>

So why am I getting the message:

org.hibernate.MappingException: Unknown entity: library.model.Person

If I try things like:

<property name="packagesToScan" value="library.model" /> 

<property name="annotatedClasses">
        <list>
            <value>library.model.Person</value>
        </list>
    </property>   

At the moment I am getting:

Jun 15, 2014 10:50:58 PM org.apache.catalina.core.ApplicationContext log INFO: Initializing Spring root WebApplicationContext Jun 15, 2014 10:51:02 PM org.apache.catalina.core.StandardContext listenerStart SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: library.services.PersonService library.controller.PersonController.personService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: library.dao.PersonDAOImpl library.services.PersonService.personDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'PersonDAOImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.hibernate.SessionFactory library.dao.PersonDAOImpl.sessionFactory; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in ServletContext resource [/WEB-INF/library-servlet.xml]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: javax/persistence/NamedStoredProcedureQuery at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4681) at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5184) at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5179) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:744)

Answer 1

Try replacing:

<property name="annotatedClasses">
    <list>
        <value>library.model.Person</value>
    </list>
</property>  

With:

<property name="packagesToScan">
   <list>
       <value>library.model</value>
    </list>
</property>

In your sessionFactory properties.

If you get an error saying the property "packagesToScan" could not be found then you should add the spring-orm library to your project. If you're using maven then you can add:

<dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-orm</artifactId>
   <version>YOUR SPRING VERSION HERE</version>
</dependency>