Hibernate declare composite primary key in JoinTable (List<>)

Question

Hibernate declare composite primary key in JoinTable (List<>)

How do I declare the composite primary key in a side table using HQL (Hibernate query language)? Previously I got one jointable declared in my class and everything worked fine, it created a composite primary key of the two columns. This is the code I used:

BEFORE (worked)

@Id
@SequenceGenerator(name="someSequence", sequenceName="SEQ_APP", allocationSize =1)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="appSequence")
@Column(name="id")
private int setting_id;

@OneToOne
private User user;

@ManyToMany
@JoinTable(
        name="tbl_settings_objectproxy",
        joinColumns = @JoinColumn(name = "id"),
        inverseJoinColumns = @JoinColumn( name = "objectproxy_id")
)
private Set<SomeObject> objectproxy;

Now I scrued everything up, I changed the Set to a List and added another side table. Now hibernate creates two side tables as it is supposed to do but it doesn't declare any primary key's... does anyone know how to fix this? This is my new code:

AFTER (it doesn't create composite primary key anymore, it doesn't even declare any primary key)

@Id
@SequenceGenerator(name="someSequence", sequenceName="SEQ_APP", allocationSize =1)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="appSequence")
@Column(name="id")
private int setting_id;

@OneToOne
private User user;


@ManyToMany
@JoinTable(
    name="tbl_settings_objectproxy",
    joinColumns = @JoinColumn(name = "id"),
    inverseJoinColumns = @JoinColumn( name = "objectproxy_id")
    )
private List<SomeObject> objectProxyForSomething;

I guess that declaring the collections as Sets rather than Lists would do it. Or you can also create your database schema by yourself, which would let you do whatever you want. Side note: HQL is the Hibernate **Query** Language. There's nothing related to a query and to HQL in your question. — JB Nizet, May 31 '12 at 11:44
How do I declare the composite primary key then ? And I don't want to change the List to Set. — Ben, May 31 '12 at 11:49
create table tbl_settings_objectproxy_for_something (id number not null, objectproxy_id number not null, constraint tbl_settings_objectproxy_for_something_pk (id, objectproxy_id)) — JB Nizet, May 31 '12 at 11:55
I dont want to create my tables manually because then the whole usefullness of hibernate go's lost because now I can just say: persist(object) and it automatically sees if the object is already in the database and needs to be update or if the object is new and will create a new entry for the object. So I dont have to write any HQL, I only have to write HQL for select queries. And it is the Set to List convertion that causes the problem indeed, I just verified that. — Ben, May 31 '12 at 12:25
Hibernate doesn't need to create the database itself to work. Hibernate will use the database you tell it to use. If the tables and the mapping match, everything will of course work as expected. I don't tell you to avoid using Hibernate. I tell you that you may create the database schema yourself if you need to. — JB Nizet, May 31 '12 at 13:37

Ben · Accepted Answer · 2012-06-04T09:30:31.320

Answers / solutions:

Change the List<> to a Set<> will do all the magic in this situation.
You can create the table manualy using HQL.
If you ensist on using List I only know a way to declare the(single) primary key using "columnDefinition" and you could set both columns to be unique together by setting the unique constraint with the "@UniqueConstraint" annotation like this:

@ManyToMany
@JoinTable(
    name="tbl_settings_objectproxy_for_something",
    joinColumns = @JoinColumn(name = "id", columnDefinition = "int primary key"),
    inverseJoinColumns = @JoinColumn( name = "objectproxy_id")
    uniqueConstraints = {@UniqueConstraint(columnNames={"id", "objectproxy_id"})}
    )
private List<SomeObject> SomeObjectProxy;

vote up the comment of JB Nizet because those are his solutions, but he gave them in a comment instead of an answer.

Hibernate declare composite primary key in JoinTable (List<>)

Hibernate declare composite primary key in JoinTable (List<>)

1 Answers1