我跟随this tutorial向我的Devise用户模型添加自定义字段，而且大部分内容似乎都运行良好。但是，当我尝试退出我的应用程序时，有时会收到错误：
Devise中的NameError :: SessionsController＃New
未初始化的常量User :: ParameterSanitizer
提取的来源（第11行）：
9 def devise_parameter_sanitizer
10 if resource_class == User
11 User::ParameterSanitizer.new(User, :user, params)
12 else
13 super
14 end
正如我所提到的，我的申请一般都很好。有时我可以在不收到此错误的情况下注销。它简直让我感到困惑！
编辑：重新启动rails服务器导致错误消息消失，但是，我正在寻找更持久的解决方案。
编辑：完整堆栈跟踪：
app/controllers/application_controller.rb:11:in 'devise_parameter_sanitizer'
devise (3.2.2) app/controllers/devise/sessions_controller.rb:40:in 'sign_in_params'
devise (3.2.2) app/controllers/devise/sessions_controller.rb:8:in 'new'
actionpack (4.0.0) lib/action_controller/metal/implicit_render.rb:4:in 'send_action'
actionpack (4.0.0) lib/abstract_controller/base.rb:189:in 'process_action'
actionpack (4.0.0) lib/action_controller/metal/rendering.rb:10:in 'process_action'
actionpack (4.0.0) lib/abstract_controller/callbacks.rb:18:in 'block in process_action'
activesupport (4.0.0) lib/active_support/callbacks.rb:443:in '_run__1105479583300404070__process_action__callbacks'
activesupport (4.0.0) lib/active_support/callbacks.rb:80:in 'run_callbacks'
actionpack (4.0.0) lib/abstract_controller/callbacks.rb:17:in 'process_action'
actionpack (4.0.0) lib/action_controller/metal/rescue.rb:29:in 'process_action'
actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:31:in 'block in process_action'
activesupport (4.0.0) lib/active_support/notifications.rb:159:in 'block in instrument'
activesupport (4.0.0) lib/active_support/notifications/instrumenter.rb:20:in 'instrument'
activesupport (4.0.0) lib/active_support/notifications.rb:159:in 'instrument'
actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:30:in 'process_action'
actionpack (4.0.0) lib/action_controller/metal/params_wrapper.rb:245:in 'process_action'
activerecord (4.0.0) lib/active_record/railties/controller_runtime.rb:18:in 'process_action'
actionpack (4.0.0) lib/abstract_controller/base.rb:136:in 'process'
actionpack (4.0.0) lib/abstract_controller/rendering.rb:44:in 'process'
actionpack (4.0.0) lib/action_controller/metal.rb:195:in 'dispatch'
actionpack (4.0.0) lib/action_controller/metal/rack_delegation.rb:13:in 'dispatch'
actionpack (4.0.0) lib/action_controller/metal.rb:231:in 'block in action'
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:80:in 'call'
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:80:in 'dispatch'
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:48:in 'call'
actionpack (4.0.0) lib/action_dispatch/routing/mapper.rb:44:in 'call'
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:71:in 'block in call'
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in 'each'
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in 'call'
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:655:in 'call'
warden (1.2.3) lib/warden/manager.rb:35:in 'block in call'
warden (1.2.3) lib/warden/manager.rb:34:in 'catch'
warden (1.2.3) 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) lib/action_dispatch/middleware/params_parser.rb:27:in 'call'
actionpack (4.0.0) 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) lib/action_dispatch/middleware/cookies.rb:486:in 'call'
activerecord (4.0.0) lib/active_record/query_cache.rb:36:in 'call'
activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in 'call'
activerecord (4.0.0) lib/active_record/migration.rb:369:in 'call'
actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in 'block in call'
activesupport (4.0.0) lib/active_support/callbacks.rb:373:in '_run__1611111079631103792__call__callbacks'
activesupport (4.0.0) lib/active_support/callbacks.rb:80:in 'run_callbacks'
actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in 'call'
actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in 'call'
actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in 'call'
actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in 'call'
actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in 'call'
railties (4.0.0) lib/rails/rack/logger.rb:38:in 'call_app'
railties (4.0.0) lib/rails/rack/logger.rb:21:in 'block in call'
activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in 'block in tagged'
activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in 'tagged'
activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in 'tagged'
railties (4.0.0) lib/rails/rack/logger.rb:21:in 'call'
actionpack (4.0.0) 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) 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) lib/action_dispatch/middleware/static.rb:64:in 'call'
railties (4.0.0) lib/rails/engine.rb:511:in 'call'
railties (4.0.0) lib/rails/application.rb:97: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'
/Users/joelbrewer/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:138:in 'service'
/Users/joelbrewer/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:94:in 'run'
/Users/joelbrewer/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/server.rb:295:in 'block in start_thread'
答案 0 :(得分：13)
在开发模式下修改User类并自动重新加载时，将销毁User :: ParameterSanitizer常量。但User :: ParameterSanitizer仅在其源文件在您的清理程序初始化程序中为require时创建。
将User::ParameterSanitizer重命名为UserParameterSanitizer，您应该没问题。
答案 1 :(得分：0)
我在开发中遇到了这个并通过重新启动我的本地服务器来解决它。