ruby on rails - Joining multiple relationships from separate tables into one association -

i have several models relevant question..

• usergrouppermission
• usergroup
• user
• userpermission
• permission

essentially, user can assigned permission through either usergroup or directly. usergroups tied specific permissions via usergrouppermission model. users tied specific permissions via userpermission model.

the end result able call user.permissions , return every permission assigned user either directly or through usergroup.

here current model

class user < activerecord::base     belongs_to :user_group      #permissions     has_many :user_permissions     has_many :user_group_permissions, :through => :user_group     has_many :permissions, :through => :user_group_permissions #and :user_permissions end 

i've search high , low solution this, can't seem find exact case. in advance!

edit: i've been told unclear i'm asking. help: user has_many :permissions, :through => :user_group_permissions , :user_permissions, can't use , join results together. i'm trying retrieve , combine results of both of relations one.

edit 2: i've been doing work. code gives desired result, i'm not sure how work potentially large databases.

  #permissions   has_many :user_permissions   has_many :user_group_permissions, :through => :user_group   #has_many :permissions, :through => :user_group_permissions   #has_many :permissions, :through => :user_permissions    def permissions     all_permissions = []     usergrouppermission.where('user_group_id = ?', user_group_id).each |ugp|       all_permissions.append(permission.find(ugp.permission_id))     end      userpermission.where('user_id = ?', id).each |p|       all_permissions.append(permission.find(p.permission_id))     end      return all_permissions   end