Consider the following database schema:
create table UserGroup ( id int not null auto_increment, name varchar(200),
primary key(id));
create table User ( id int not null auto_increment, name varchar(200),
groupId int not null, primary key(id));
User.groupId = UserGroup.id, so a user can only be a member of one group, but a usergroup can exist of many users. Fine so far, let's make the entities in Hibernate. Here's User:
@Entity
@Table(name = "User")
public class User {
@Id
@Column(name="id", nullable = false)
private Integer id;
@Column(name="name", length = 200, nullable = true)
private String name;
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name = "groupId", nullable = false, insertable=false, updatable=false)
@ForeignKey(name="FK_GroupId")
private UserGroup userGroup;
/* Getters, Setters, toString, equals & hashCode */
}
Here's UserGroup:
@Entity
@Table(name = "UserGroup")
public class UserGroup {
@Id
@Column(name="id", nullable = false)
private Integer id;
@Column(name="name", length = 200, nullable = true)
private String name;
@OneToMany(fetch=FetchType.EAGER)
private List<User> users;
/* Getters, Setters, toString, equals & hashCode */
}
Now I'll get an error "Table mydb.usergroup_user' doesn't exist" because it expects a join-table. My data structure is "set in stone" due to interoperability with other applications that this application will replace, so I won't be making a join-table. Also, it should not be needed. How can I make a List<User> users that simply is a list of User where User.groupId == UserGroup.Id?
