JPA and EJB - OneToMany problem

Question

Hello, I try to build simple Java EE application that uses JPA + EJB3 and Stripes. It's a little address book. I'm using 2 JPA entities, Person and Email. Every person can have more emails, but each email can only belong to one person. My entities looks like this (with default setters and getters):

Person.java:

@Entity
public class Person implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;
    @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "person")
    private Collection<Email> emails; ... }

Email.java:

@Entity
public class Email implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String note;
    private String address;
    @ManyToOne
    private Person person; ... }

But when I try to show the list of every person and all their emails, I can't get emails to show. This is how I'm trying to print them:

<c:forEach items="${actionBean.people}" var="person">
  <tr>
    <td><c:out value="${person.name}"/></td>
    <td>
      <c:forEach items="${person.email}" var="email">
          <c:out value="${email.address}"/><c:out value="${email.note}"/>
      </c:forEach>
    </td>
    </tr>
</c:forEach>

Any idea, how to solve this?

Answer 1

Does your Person class have a getEmail() method or a getEmails() method? Given the variable name of emails I would expect a Person.getEmails() given the attribute name, but your JSTL is looking for getEmail().

If that's not the problem, I believe you might need to add a @JoinColumn annotation to your Email class, and add a column to the email table that refers back to the person id. This is how I've done all my ManyToOne annotations. An example ManyToOne can be found here.