休眠执行多个查询

Question

I am having a model User and having id and other properties in it.

public class User{
      int id;
      .....

      @OneToOne(fetch=FetchType.LAZY)
      @JoinColumn(name="id")
      private UserLocation userLocationObj;

}

UserLocation is the model class and like the UserLocation there are more 5-6 properties with same annotations to make the association with the User class.

In the UserLocation model class and other model classes also I did the one to one mapping with the user class .

And also other properties along with their getter and setter. And when I am trying to getting the object of User class by using id it is executing n number of queries and then showing stackoverflow error . Why so ??

My User table Structure is : User

+----------------------+-----
| Field                | Key|
+----------------------+-----
| id                   | PRI| 
| userName             |    |             
| first_name           |    |             
| middle_name          |    |            
| last_name            |    |            
| dateOfBirth          |    |            
| gender               |    |            
| city                 |    |            
| email                |    |
+----------------------+----+

My UserLocation table Structure is :
UserLocation
+-----------------++-----
| Field           | Key |
+-----------------+------
| id              | PRI |
| user_id         |     |
| current_city    |     |
| current_country |     |
| latitude        |     |
| longitude       |     |
| iso_location    |     |
+-----------------+-----+

UserId in the UserLocation is the id of the Users table .

Thanks

Answer 1

The problem here is connected to the name of your column: You are telling hibernate that @JoinColumn(name="id") : this means that in the table User there is a field named id , that joins in the table UserLocation , which is not what is your database structure.

You have instead the object User in the UserLocation table, so this is represented by

public class UserLocation{
      int id;
      .....

      @OneToOne(fetch=FetchType.LAZY)
      @JoinColumn(name="user_id")
      private User user;

}

Then, you can let the User class know that it has connected the UserLocation class with this:

public class User{
      int id;
      .....

      @OneToOne(fetch=FetchType.LAZY, mappedBy = "user_id")
      private UserLocation userLocationObj;

}

The JoinColumn annotation indicates that the class is the owner of the relation, so in this case the owner is UserLocation , whereas the mappedBy represent the other side of the linking.