When doing orm.xml, I found that the order of Joincolumn and Cascade should be in order, otherwise it will encountered some problem.

Here is my definition of some classes, Customer and CreditCard.

package com.titan.domain;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name=”CUSTOMER_TABLE”)
public class Customer implements java.io.Serializable {
    private int id;
    private String firstName;
    private String lastName;
    private Address address;
    private CreditCard creditCard;
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    @OneToOne(cascade={CascadeType.ALL})
    @JoinColumn(name=”ADDRESS_ID”)
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
    @OneToOne(cascade={CascadeType.ALL})
    @JoinColumn(name=”CREDIT_CARD_ID”)
    public CreditCard getCreditCard() {
        return creditCard;
    }
    public void setCreditCard(CreditCard creditCard) {
        this.creditCard = creditCard;
    }
}

package com.titan.domain;

import java.util.Date;

import javax.persistence.Id;
import javax.persistence.OneToOne;

public class CreditCard implements java.io.Serializable {

    private int id;
    private Date expiration;
    private String number;
    private String name;
    private String organization;
    private Customer customer;
    @Id
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public Date getExpiration() {
        return expiration;
    }
    public void setExpiration(Date expiration) {
        this.expiration = expiration;
    }
    public String getNumber() {
        return number;
    }
    public void setNumber(String number) {
        this.number = number;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getOrganization() {
        return organization;
    }
    public void setOrganization(String organization) {
        this.organization = organization;
    }
    @OneToOne(mappedBy=”creditCard”)
    public Customer getCustomer() {
        return customer;
    }
    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
}

Here is my orm.xml, placed below META-INF

<entity-mappings   
   xmlns=”http://java.sun.com/xml/ns/persistence/orm”
   xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
   xsi:schemaLocation=”http://java.sun.com/xml/ns/persistence/orm orm_1_0.xsd” 
   version=”1.0″> 
<entity class=”com.titan.domain.Customer” access=”PROPERTY”>
      <attributes>
         <id name=”id”>
            <generated-value/>
         </id>
      <one-to-one name=”creditCard”
                     target-entity=”com.titan.domain.CreditCard”
                     fetch=”LAZY”>
            <join-column name=”CREDIT_CARD_ID”/>
            <cascade>
                <cascade-all />
            </cascade>
         </one-to-one>
      </attributes>
   </entity>
   <entity class=”com.titan.domain.CreditCard” access=”PROPERTY”>
      <attributes>
         <id name=”id”>
            <generated-value/>
         </id>
      <one-to-one name=”customer”
                     target-entity=”com.titan.domain.Customer”
                     mapped-by=”creditCard”/>
      </attributes>
   </entity>

</entity-mappings> 

To note that, cascade element should be below of join-column element, and inside cascade element it contains cascade-all, cascade-persist, cascade-merge, cascade-remove, cascade-refresh

Reference Site: http://markmail.org/message/73xeygrwcslyekwn

Just learnt EJB for half month. Just learnt how to create Entity class. When deploys, JBOSS always give me error. Now I found a solution, The problem is sometimes persistence.xml lost the XML Schema, the full persistence.xml can be like this:

<?xml version=”1.0″ encoding=”UTF-8″?>

<persistence
    xmlns=”http://java.sun.com/xml/ns/persistence”
    xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
    xsi:schemaLocation=”http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd”
    version=”1.0″>
    <persistence-unit name=”calculator”>
    <jta-data-source>java:/DefaultDS</jta-data-source>
    <properties>
        <property name=”hibernate.hbm2ddl.auto” value=”create-drop” />
    </properties>
    </persistence-unit>
</persistence>

Hope anyone who faced this problem can solve your problem.