@ManyToMany remove records from join rows

[Marcus Casey]

How do I remove a record from the join table in a many-to-many relationship?

I am using JPA. I have created a many-to-many relationship between users and groups. A MyUser can be in more than one MyGroup and a MyGroup can have more than one MyUser. Pretty straightforward.

Here is some of my code for MyUser:

@Entity
@Table(name="my_user") 
public class MyUser implements Serializable{
    
    @Id()
    @GeneratedValue(strategy=GenerationType.SEQUENCE)
    @Column(name="my_user_id")
    private Long myUserId;
    @Column(name="user_name")
    private String userName;
    @ManyToMany(cascade={CascadeType.ALL},fetch=FetchType.EAGER)
    @JoinTable(name="my_user_group",
               joinColumns={@JoinColumn(name="my_user_id")},
               inverseJoinColumns={@JoinColumn(name="my_group_id")})
    private List<MyGroup> groups = new ArrayList<MyGroup>();

and for MyGroup:

@Entity
@Table(name="my_group")
public class MyGroup implements Serializable{
    
    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE)
    @Column(name="my_group_id")
    private Long groupId;
    @Column(name="group_name")
    private String groupName;

As you can tell from the code, I have a join table called my_user_group that just has the foreign keys from each table. (You may also notice it is unidirectional. I don't have a need to list the users by group, only the groups by user).

Now to my question--how do I remove a group from a user? I notice that if I remove a group from the List on my object and the perform a merge(), the foreign key records for the removed group are still there.

Any suggestions would be most welcome.

[Mike Keith]

Marcus,

You are checking for the rows after committing the transaction, right? The rows won't typically be removed until commit-time. Maybe if you could post your code I could see what else could be going wrong. Your mappings look okay.