jpa - Hibernate problem - "Use of @OneToMany or @ManyToMany targeting an unmapped class"

Question

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

I have 2 entities, Section and ScopeTopic. The 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!

Answer 1

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.