我正在关注 Ryan 对 RailsCast 的设计和omniauth（第 235 集设计和 omniauth 修订）。当我尝试使用 twitter 登录时，我不断收到标题中的错误。
def self.new_with_session(params, session)
if session["devise.user_attributes"]
new(session["devise.user_attributes"], without_protection: true) do |user|
user.attributes = params
user.valid?
end
完整跟踪：
C:/Ruby200-x64/lib/ruby/gems/2.0.0/bundler/gems/mongoid-fe7f43430580/lib/mongoid/document.rb:106:in `initialize'
devise (3.0.0.rc) lib/devise/models/confirmable.rb:46:in `initialize'
app/models/user/user.rb:58:in `new'
app/models/user/user.rb:58:in `new_with_session'
devise (3.0.0.rc) app/controllers/devise/registrations_controller.rb:86:in `build_resource'
devise (3.0.0.rc) app/controllers/devise/registrations_controller.rb:7:in `new'
actionpack (4.0.0.rc1) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (4.0.0.rc1) lib/abstract_controller/base.rb:189:in `process_action'
actionpack (4.0.0.rc1) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.0.0.rc1) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (4.0.0.rc1) lib/active_support/callbacks.rb:442:in `_run__1463920666__process_action__callbacks'
activesupport (4.0.0.rc1) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.0.rc1) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (4.0.0.rc1) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.0.0.rc1) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.0.0.rc1) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.0.0.rc1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.0.0.rc1) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.0.0.rc1) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.0.0.rc1) lib/action_controller/metal/params_wrapper.rb:245:in `process_action'
actionpack (4.0.0.rc1) lib/abstract_controller/base.rb:136:in `process'
actionpack (4.0.0.rc1) lib/abstract_controller/rendering.rb:44:in `process'
actionpack (4.0.0.rc1) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.0.0.rc1) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.0.0.rc1) lib/action_controller/metal.rb:231:in `block in action'
actionpack (4.0.0.rc1) lib/action_dispatch/routing/route_set.rb:80:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/routing/route_set.rb:80:in `dispatch'
actionpack (4.0.0.rc1) lib/action_dispatch/routing/route_set.rb:48:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/routing/mapper.rb:44:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.0.0.rc1) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.0.0.rc1) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/routing/route_set.rb:654:in `call'
omniauth (1.1.4) lib/omniauth/strategy.rb:184:in `call!'
omniauth (1.1.4) lib/omniauth/strategy.rb:164:in `call'
C:/Ruby200-x64/lib/ruby/gems/2.0.0/bundler/gems/mongoid-fe7f43430580/lib/rack/mongoid/middleware/identity_map.rb:34:in `block in call'
C:/Ruby200-x64/lib/ruby/gems/2.0.0/bundler/gems/mongoid-fe7f43430580/lib/mongoid/unit_of_work.rb:39:in `unit_of_work'
C:/Ruby200-x64/lib/ruby/gems/2.0.0/bundler/gems/mongoid-fe7f43430580/lib/rack/mongoid/middleware/identity_map.rb:34:in `call'
warden (1.2.1) lib/warden/manager.rb:35:in `block in call'
warden (1.2.1) lib/warden/manager.rb:34:in `catch'
warden (1.2.1) lib/warden/manager.rb:34:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/flash.rb:241:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/cookies.rb:486:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.0.0.rc1) lib/active_support/callbacks.rb:392:in `_run__1122738349__call__callbacks'
activesupport (4.0.0.rc1) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/reloader.rb:64:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.0.0.rc1) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.0.rc1) lib/rails/rack/logger.rb:21:in `block in call'
activesupport (4.0.0.rc1) lib/active_support/tagged_logging.rb:67:in `block in tagged'
activesupport (4.0.0.rc1) lib/active_support/tagged_logging.rb:25:in `tagged'
activesupport (4.0.0.rc1) lib/active_support/tagged_logging.rb:67:in `tagged'
railties (4.0.0.rc1) lib/rails/rack/logger.rb:21:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.0.0.rc1) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.0.0.rc1) lib/action_dispatch/middleware/static.rb:64:in `call'
railties (4.0.0.rc1) lib/rails/engine.rb:511:in `call'
railties (4.0.0.rc1) lib/rails/application.rb:96:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
C:/Ruby200-x64/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service'
C:/Ruby200-x64/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run'
C:/Ruby200-x64/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'
RoR 和所有这一切仍然很新，所以任何帮助都将受到欢迎。