关联表中的rails 3 load属性

Question

I have 3 basic models: Users, Permissions and an association model called UserPermissions so user has_many :permissions, through :user_permissions

My user permissions table holds the user_id, permission_id and also a privilege attribute which is a bitmask. Now, when I query the user for his permissions I do something like this:

@permissions = user.permissions

and I get a nice collection of the associated permissions of that given user. What I would like to do is also add the privilege field to the results so instead of this result

{
  "id": 1,
  "name": "User permissions",
  "short_name": "user_permissions"
}

I need something like this:

{
  "id": 1,
  "name": "User permissions",
  "short_name": "user_permissions",
  "privilege": "..whatever the bitmask converts to"
}

I hope i'm making sense. Any ideas?

Answer 1

You could just add a method to the permission class to compose your hash. Something like

class Permission
    ....

    def attributes_with_privilege
        attributes.merge( 'privilege': user_permission.privilege )
    end

   ...
end