Styjun

I'm finding my feet with Hibernate Annotations and I've hit a problem I hope some one can help with.

I have 2 entities, Section and ScopeTopic. Section has a List class member, so a One to Many relationship. When I run my unit test I am getting this exception:

Use of @OneToMany or @ManyToMany targeting an unmapped class: com.xxx.domain.Section.scopeTopic[com.xxx.domain.ScopeTopic]

I would assume that the error implies that my ScopeTopic entity isn't mapped to a table? I can't see with I have done wrong. Here are the Entity classes:

@Entity
public class Section 
 private Long id;
 private List<ScopeTopic> scopeTopics;

 public Section() 

 @Id
 public Long getId() 
 return id;
 

 public void setId(Long id) 
 this.id = id;
 

 @OneToMany
 @JoinTable(name = "section_scope", joinColumns = @JoinColumn(name="section_id"),
 inverseJoinColumns = @JoinColumn(name="scope_topic_id") )
 public List<ScopeTopic> getScopeTopic() 
 return scopeTopic;
 

 public void setScopeTopic(List<ScopeTopic> scopeTopic) 
 this.scopeTopic = scopeTopic;
 

@Entity
@Table(name = "scope_topic")
public class ScopeTopic 
 private Long id;
 private String topic;

 public ScopeTopic() 

 @Id
 public Long getId() 
 return id;
 

 public void setId() 
 this.id = id;
 

 public String getTopic() 
 return topic;
 

 public void setTopic(String topic) 
 this.topic = topic;
 

I'm pretty sure it's my own lack of understanding that's at fault so some guidance would be great, thanks!

Your annotations look fine. Here are the things to check:

• make sure the annotation is javax.persistence.Entity, and not org.hibernate.annotations.Entity. The former makes the entity detectable. The latter is just an addition.




• if you are manually listing your entities (in persistence.xml, in hibernate.cfg.xml, or when configuring your session factory), then make sure you have also listed the ScopeTopic entity




• make sure you don't have multiple ScopeTopic classes in different packages, and you've imported the wrong one.

Your entity may not listed in hibernate configuration file.

Mine was not having @Entity on the many side entity

@Entity // this was commented
@Table(name = "some_table")
public class ChildEntity 
 @JoinColumn(name = "parent", referencedColumnName = "id")
 @ManyToOne
 private ParentEntity parentEntity;

Mostly in Hibernate , need to add the Entity class in hibernate.cfg.xml like-

<hibernate-configuration>
 <session-factory>

 ....
 <mapping class="xxx.xxx.yourEntityName"/>
 </session-factory>
</hibernate-configuration>

I had the same problem and I could solve it by adding the entity into persistence.xml.
The problem was caused due to the fact that the entity was not added to the persistence config. Edit your persistence file:

<persistence-unit name="MY_PU" transaction-type="RESOURCE_LOCAL">
<provider>`enter code here`
 org.hibernate.jpa.HibernatePersistenceProvider
 </provider>
<class>mypackage.MyEntity</class>

...

In my case a has to add my classes, when building the SessionFactory, with addAnnotationClass

Configuration configuration.configure();
StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());
SessionFactory sessionFactory = configuration
 .addAnnotatedClass(MyEntity1.class)
 .addAnnotatedClass(MyEntity2.class)
 .buildSessionFactory(builder.build());