What is the appropriate mapping strategy for the below scenario.
Following are the DB tables and the java code i want them to map.

Any pointers would be of great help.

Thanks


GROUP
groupid | name
1 | group1
2 | group2

GROUP_OBJ
groupid | objecttype | objectid
1 | OBJ1 | 1
1 | OBJ1 | 2
1 | OBJ2 | 1
1 | OBJ3 | 3
2 | OBJ1 | 1
2 | OBJ2 | 2

@Entity
class Group {
@OneToMany
List<ObjectID> objectIDs;
}

Thanks for your response.
Can you clarify your solution.

I'm more interested in the mapping for GroupObjects.
Appreciate any comments on the topic

Thanks

If I'm understanding correctly, the GroupObjects class is meant to be a join between Group and ObjectIDs. Here, the join (either by table or FK) will be managed for you by Hibernate.

Yes, GroupObjects is a join between Group and ObjectIds.
Let me explain my problem more clearly.

I want to access (set/get) objectIds based on ObjectType.

group.setObjectIds(ObjectType, Collection<ObjectIds>)

Collection<ObjectIds> group.getObjectIds(ObjectType)

ObjectType is an enum

If i have to adopt your solution then, to get the ObjectIds of a particular ObjectType, i have to iterate through the complete collection.
Similarly if i want to update only Objectids of a particular type then its not straight forward.

that way my ideal requirement will be a kind of map (but the mapping for this appears more complex)

Ah, I see. I've mapped Maps in Hibernate, but it was a Map<String, List<Foo>> (simple type to list of user type), so I don't if this applies to you but here goes.

I had to create a class, call it FooList, to encapsulate the List<Foo>, then - in the class with the Map member - declare it as:

@OneToMany(cascade=CascadeType.ALL)
private Map<String, FooList> foos;

I never found a way to directly do Map<String, List<Foo>>. HTH.

Further research supports my initial response:

http://blog.xebia.com/2007/10/05/mappin ... hibernate/

Hi Jason,

Can you plese provide the full annotaitons you used for your java map? So far I have used:

@org.hibernate.annotations.CollectionOfElements
@JoinTable(
name = "zad_category_keywords",
joinColumns = @JoinColumn(name = "Catalog_Id")
)
@org.hibernate.annotations.MapKey(
columns = @Column(name="Shop_Category_Id")
)
@Column(name = "Keywords")
@org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
private Map<ShopCategory, String> categoryToKeywordsMap;

But the cascade delete is not working. Apparently it only applies to @OneToMany or @ManyToMany. So I want to adapt your @OneToMany annotations to get this working.

Many thanks
Jeremy

I used

@OneToMany(cascade=CascadeType.ALL)

Hi,

Thanks for your fast reply.

You just used this single annotation? How did you specify the column names, join table etc.? Could you provide the code snippet which specifies the map too?

Many thanks
Jeremy

Hi,

I tried the Map of Sets (using MultiMap) solution that you pointed to.
See below for the mapping. In spite of cascade option set the AclObject is not getting saved and i get the following errors
“object references an unsaved transient instance - save the transient instance before flushing”



Any pointers would be of great help
Also, if you could elaborate on your approach (Map<String, FooList>).

Thanks