EJB 3 OneToMany with Composite Key

[deanouk]

Hi all,

Having a problem setting up my first EJB 3 OneToMany relationship with a composite key.

Here's the error:
14:09:01,812 WARN [JDBCExceptionReporter] SQL Error: 957, SQLState: 42000
14:09:01,812 ERROR [JDBCExceptionReporter] ORA-00957: duplicate column name

The 'One' Entity:

import javax.persistence.*;
import java.io.Serializable;
import java.util.Collection;



@Entity
@Table(name = "COMMS_MESSAGES")
public class CommsMessage implements Serializable
{

 private int messageId;

 /**
 * Any attachments.
 */
 private Collection<CommsAttachment> commsAttachments;


 public CommsMessage()
 {
 }


 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 public int getMessageId()
 {
 return messageId;
 }

 public void setMessageId(int messageId)
 {
 this.messageId = messageId;
 }

 @OneToMany(mappedBy = "commsMessage", cascade = {CascadeType.PERSIST, CascadeType.REMOVE}, fetch=FetchType.LAZY)
 public Collection<CommsAttachment> getCommsAttachments()
 {
 return commsAttachments;
 }

 public void setCommsAttachments(Collection<CommsAttachment> commsAttachments)
 {
 this.commsAttachments = commsAttachments;
 }



}

The 'Many' Entity:

import javax.persistence.*;
import java.io.Serializable;

/**
 * Comms Message Entity Bean
 *
 * @author Dean Pullen
 * @since 03-Jul-2007
 */
@Entity
@Table(name = "COMMS_MESSAGE_RECIPIENTS")
@IdClass(CommsMessageRecipientPK.class)
public class CommsMessageRecipient implements Serializable
{
 private CommsMessage commsMessage;

 private int messageId;

 private int recipientUserId;


 public CommsMessageRecipient()
 {
 }

 @ManyToOne
 @JoinColumn(name = "messageid")
 public CommsMessage getCommsMessage()
 {
 return commsMessage;
 }

 public void setCommsMessage(CommsMessage commsMessage)
 {
 this.commsMessage = commsMessage;
 }

 @Id
 public int getMessageId()
 {
 return messageId;
 }

 public void setMessageId(int messageId)
 {
 this.messageId = messageId;
 }

 @Id
 public int getRecipientUserId()
 {
 return recipientUserId;
 }

 public void setRecipientUserId(int recipientUserId)
 {
 this.recipientUserId = recipientUserId;
 }
}

The Composite Key:

package com.msp.ejb.lms.comms;

import java.io.Serializable;

public class CommsMessageRecipientPK implements Serializable
{
 private int messageId;

 private int recipientUserId;


 public CommsMessageRecipientPK()
 {
 }

 public CommsMessageRecipientPK(int messageId, int recipientUserId)
 {
 this.messageId = messageId;
 this.recipientUserId = recipientUserId;
 }


 public int getMessageId()
 {
 return messageId;
 }

 public void setMessageId(int messageId)
 {
 this.messageId = messageId;
 }

 public int getRecipientUserId()
 {
 return recipientUserId;
 }

 public void setRecipientUserId(int recipientUserId)
 {
 this.recipientUserId = recipientUserId;
 }


 public boolean equals(Object o)
 {
 if (this == o) return true;
 if (o == null || getClass() != o.getClass()) return false;

 CommsMessageRecipientPK that = (CommsMessageRecipientPK) o;

 return messageId == that.messageId && recipientUserId == that.recipientUserId;

 }

 public int hashCode()
 {
 int result;
 result = messageId;
 result = 31 * result + recipientUserId;
 return result;
 }
}

As you can see, I'm trying to map the CommsMessage to multiple CommsRecipients using the 'messageid' value found in both tables.

Any help greatly appreciated.

[deanouk]

That first set of code should have:

@OneToMany(mappedBy = "commsMessage", cascade = {CascadeType.PERSIST, CascadeType.REMOVE}, fetch=FetchType.LAZY)
 public Collection<CommsMessageRecipient> getCommsMessageRecipients()
 {
 return commsMessageRecipients;
 }

 public void setCommsMessageRecipients(Collection<CommsMessageRecipient> commsMessageRecipients)
 {
 this.commsMessageRecipients = commsMessageRecipients;
 }

Ignore the CommsAttachment object - thats meant to be having the same relationship but I took it out for this example.

[waynebaylor]

if i remember correctly, the @OneToMany relationship will, by default, create a table for the "many" side which will contain a foreign key referencing the "one" side.

so, since messageId is the PK for CommsMessage the table representing CommsMessageRecipient will have two columns named messageId: one as the FK referencing CommsMessge and another as part of its own PK.