有表users和表orders，rails生成的关联表是orders_users，现在可不可以在users_controller.rb中通过User更新orders_users表中的字段值，要怎么操作……
关联两张表时，会有生成以下的方法，更新orders_users也是通过以下方法操作
user.orders<<(object, ...)
user.orders.delete(object, ...)
user.orders.destroy(object, ...)
user.orders=objects
user.orders_singular_ids
user.orders_singular_ids=ids
user.orders.clear
user.orders.empty?
user.orders.size
user.orders.find(...)
user.orders.where(...)
user.orders.exists?(...)
user.orders.build(attributes = {})
user.orders.create(attributes = {})
user.orders.create!(attributes = {})http://guides.rubyonrails.org...
http://guides.ruby-china.org/...