How to write @ManyToMany/@JoinTable if join table has third

[gus888]

Hi All,

I have a question on how to write @ManyToMany and @JoinTable code, e.g. a join table is

table member_party (
member_id,
party_id,
joined_date)

how to modify the following codes:

@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, fetch = FetchType.EAGER)
 @JoinTable(table = @Table(name = "member_party"),
 joinColumns = {@JoinColumn(name = "MEMBER_ID")},
 inverseJoinColumns = {@JoinColumn(name = "PARTY_ID")})

Many thanks for any help!

[gus888]

Hi all,

Sorry for my question is unclear. My question is: if join table has extra attributes besides the two foreign key (shown above), how to map its @ManyToMany code in entity bean. Thank you very much in advance.

[gus888]

Hi all,

I found a little idea in the Hibernate in Action book, it is on the section of Using a collection of components for a many-to-many association in Chapter 6. It seems that I need to create a new class for the joint table. Any further suggestion is appreciated.

GUS

[chrismalan]

Hi Gus,

I see you posted in March. You may never see this response.

Yes, you have to explicitly create another @Entity bean, say MembershipDetails

Besides that, create a bean with an @Embeddable annotation as a composite primary key

@Embeddable
public class PartyMemberPK implements Serializable{
 private String member_id, party_id;

 public PartyMemberPK(){}
 public PartyMemeberPK(String member_id, String party_id){
 use your getters and setters to set these
 }
}

Then use PartyMemberPK as a composite PK in MembersipDetails and add the date you want, as well.

Hope this helps.

[mazz]

I've given up using @ManyToMany. I started out with them and they work fine, but I always ended up needing to put in extra attributes thus running into this problem.

Now, even for my many-to-many relationships, I start out with @ManyToOne/@OneToMany with an explicity @Entity for the association table in the middle.