JPA one_to_one relationship not retrieve the auto increment - mysql

Question

I have 2 Mysql tables users and empires,
users
CREATE TABLE `users` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`email` varchar(45) CHARACTER SET utf8 NOT NULL,
`password` varchar(12) CHARACTER SET utf8 NOT NULL,
`country` varchar(25) CHARACTER SET utf8 NOT NULL,
`activated` tinyint(3) unsigned NOT NULL DEFAULT '0',
`activationcode` varchar(45) CHARACTER SET utf8 NOT NULL DEFAULT '',
PRIMARY KEY (`id`),
UNIQUE KEY `email_UNIQUE` (`email`),
KEY `email` (`email`)
) ENGINE=InnoDB AUTO_INCREMENT=19 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
and empires
CREATE TABLE `empires` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`pid` int(10) unsigned NOT NULL,
`name` varchar(45) CHARACTER SET utf8 NOT NULL,
`notes` varchar(90) CHARACTER SET utf8 NOT NULL,
`world` tinyint(3) unsigned NOT NULL,
`island` smallint(5) DEFAULT NULL,
`population` int(10) unsigned DEFAULT '20',
`gold` decimal(20,0) DEFAULT '500',
`percent` decimal(9,5) DEFAULT '50.00000',
`logo` varchar(30) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
PRIMARY KEY (`id`,`pid`),
KEY `name` (`name`),
KEY `world` (`world`),
KEY `FK_pid` (`pid`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
and i have these entities :
package boddooo.entity;
import java.io.Serializable;
import javax.persistence.*;
#Entity
#Table(name="users")
#NamedQuery(name="User.findAll", query="SELECT u FROM User u")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private int activated=1;
private String activationcode="";
private String country;
private String email;
private String password;
public User(){}
public User(int id,String email,String password,String country) {
this.id=id;
this.email=email;
this.password=password;
this.country=country;
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public int getActivated() {
return this.activated;
}
public void setActivated(int activated) {
this.activated = activated;
}
public String getActivationcode() {
return this.activationcode;
}
public void setActivationcode(String activationcode) {
this.activationcode = activationcode;
}
public String getCountry() {
return this.country;
}
public void setCountry(String country) {
this.country = country;
}
public String getEmail() {
return this.email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPassword() {
return this.password;
}
public void setPassword(String password) {
this.password = password;
}
}
and
package boddooo.entity;
import java.io.Serializable;
import java.math.BigDecimal;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
#Entity
#Table(name="empires")
#NamedQuery(name="Empire.findAll", query="SELECT e FROM Empire e")
public class Empire implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private int pid;
private BigDecimal gold=BigDecimal.valueOf(500);
private String logo="";
private String name;
private String notes;
private BigDecimal percent=BigDecimal.valueOf(50.0000);
private int population=10;
private int world;
private int island;
#OneToOne
#PrimaryKeyJoinColumn(name="pid")
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public Empire(){}
public Empire(int id,String name,String logo,String notes,int world) {
this.id=id;
this.name=name;
this.logo=logo;
this.notes=notes;
this.world=world;
}
public int getPid() {
return pid;
}
public void setPid(int pid){
this.pid=pid;
}
public int getWorld() {
return world;
}
public void setWorld(int world) {
this.world = world;
}
public int getIsland() {
return island;
}
public void setIsland(int island) {
this.island = island;
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public BigDecimal getGold() {
return this.gold;
}
public void setGold(BigDecimal gold) {
this.gold = gold;
}
public String getLogo() {
return this.logo;
}
public void setLogo(String logo) {
this.logo = logo;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getNotes() {
return this.notes;
}
public void setNotes(String notes) {
this.notes = notes;
}
public BigDecimal getPercent() {
return this.percent;
}
public void setPercent(BigDecimal percent) {
this.percent = percent;
}
public int getPopulation() {
return this.population;
}
public void setPopulation(int population) {
this.population = population;
}
}
and this function to insert the new objets to the database
public void createUser() throws NamingException, NotSupportedException, SystemException, SecurityException, IllegalStateException, RollbackException, HeuristicMixedException, HeuristicRollbackException{
Context icontext=new InitialContext();
ut=(UserTransaction)icontext.lookup("java:comp/UserTransaction");
ut.begin();
User user=new User();
user.setEmail(email);
user.setPassword(password);
user.setCountry(country);
em.persist(user);
Empire emp=new Empire();
emp.setName(empirename);
emp.setNotes(empirenotes);
emp.setLogo(empirelogo);
emp.setWorld(worldid);
emp.setUser(user);
em.persist(emp);
ut.commit();
}
this is one to one relationship which
empires.pid=users.id
but when i call this method it insert users and empires but the pid field in empires has 0 value instead of the auto increment value.
am i miss something? please help

Answer 1

#PrimaryKeyJoinColumn indicates that the field used is this entities primary key, and as such is effectively read-only. This is mostly used when you have an entity that spans multiple tables.
#JoinColumn is what you should be using as it indicates the specified column is a traditional foreign key and that you want the target value to be used to set this field.
#OneToOne
#JoinColumn(name="pid")
private User user;

Answer 2

You should use #JoinColumn(name="fk_id") along with #OneToOne. More details at JSR 317: JavaTM Persistence API, Version 2.0