JPA OneToOne join issue

Question

Here is my SimpleCost Entity

@Entity
@Table(name="Simplecost")
public class SimpleCost {
@Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)  
 private Long id;
 private Long userId;
 private Long cost;
 @OneToOne(cascade=CascadeType.ALL,fetch = FetchType.EAGER)
 @JoinColumn(name = "userId")
 private UserBare user;
}

UserBare:

@Entity
@Table(name="user")
public class UserBare{
 @Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)  
 private Long id;
 private Long userId;
 private String fName;
 private String lName;
}

So I'm having an trouble populating SimpleCost.user attribute. I need to use SimpleCost.userId to retreive the user table data and fill the SimpleCost.user object. Here is my database structure.

Database Tables: User

CREATE TABLE `user` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`fName` varchar(100) DEFAULT NULL,
`lName` varchar(100) DEFAULT NULL,
`mName` varchar(100) DEFAULT NULL,
`title` varchar(100) DEFAULT NULL,
`email` varchar(100) DEFAULT NULL,
 PRIMARY KEY (`id`),
 UNIQUE KEY `id_UNIQUE` (`id`)
 ) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=latin1;
 /*!40101 SET character_set_client = @saved_cs_client */;

simplecost

CREATE TABLE `simplecost` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`userId` bigint(20) DEFAULT NULL,
`liableCost` decimal(10,2) DEFAULT NULL,
`isActive` tinyint(1) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `id_UNIQUE` (`id`),
KEY `fk_simplecost_user1_idx` (`userId`),
CONSTRAINT `fk_simplecost_user` FOREIGN KEY (`userId`) REFERENCES `user`      (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1;
/*!40101 SET character_set_client = @saved_cs_client */;

Answer 1

You don't need the 'userId' columns defined in your Entity (java class). The one in UserBare is obviously useless and the one in SimpleCost will be created/used because of the @JoinColumn(name = "userId") you added to the 'user' field'

Remove private Long userId; from both Entity declaration.

Other than that, you will need to define what is "having an trouble populating SimpleCost.user attribute".