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Hibernate version:
3


Hi

Sorry for the lame n dumb question ..

I'm pretty new to hibernate ..actually starting off.. and have this question of how to do mappings.. I did search the forums but couldnt find exactly what I was looking for..

this is the scenario

A 'User' in the webapp can have multiple 'Role's.. say like admin, reviewer etc.

I have 3 classes

User [ userid, name, pwd , roles,.....]
Role [ roleid, description ]
UserRoles [ userid, roleId]


and three tables

User (id, name, pwd.... ) (pl note that theres no 'roles')
Role (roleId, description )
UserRoles( userid, roleId)

I presume that there must be a one-to-many mapping from User to UserRoles and many-to-one from Roles to User


Is this approach correct .. ? Id like to see how mappings look like

edit
===
Do we need this three class approach ?

actually a many to many mapping might make more sense.

A user can have multiple roles, but each of those roles would apply to many users.

And I'm sure there will come a time when you need a list of all users with a specific role, rather than all roles for a specific user.

Thanks.. Im not trying to quiz you, but I'm not able to get this .. why should a one-to-many relation be tweaked to become a many-to-many ?

Hi,

I think jwenting is right - your UserRoles-Class doesn't make that much sense form an object-oriented point of view. The only "real" business-objects are the Users and their Roles and these have a many-to-many-relationship. The UserRoles are some artificial construct needed to represent the many-to-many-relationship in a relational model - but why should you introduce this into an object-model where it isn't needed (if you do need it except for representing the relationships you might as well forget this post).
Overall, we aren't tweaking a one-to-many-relation to become many-to many. You're tweaking an existing many-to-many-realtionship to become two seperate relations (one-to-many and many-to-one).
So I'd also suggest you eliminate your UserRoles-class (if possible) and model a many-to-many-relationship between User and Role classes.
You will still need the UserRoles-table(!) as an association-table!

Greets

piet

thnx a tonne piet .. that explains it