通过关联对象创建现有模型的新对象的麻烦答案

【问题标题】：troubles creating a new object of existing model through association object通过关联对象创建现有模型的新对象的麻烦
【发布时间】：2014-04-27 21:19:10
【问题描述】：

我正在尝试通过关联创建一个新对象：

def create
  @enhancement = current_user.enhancements.create enhancement_params

  if @enhancement.save!
    redirect_to enhancements_path, notice: "Mission Control has receieved your request"
  else
    redirect_to enhancements_path, notice: "Danger! Mission Control could not receive your request!"
  end
end

我得到的错误是：

wrong number of arguments (1 for 0)

我也试过

@enhancement = current_user.enhancements.new enhancement_params

然后供您参考，这里是我传入的强参数

def enhancement_params
  params.require(:enhancement).permit(:name, :description, :user_id, :status)
end

在关联方面，模型增强属于_用户模型，而用户模型有_许多增强。

我不知道我做错了什么并且偷偷怀疑我错过了一些超级简单的东西，但我已经浪费了足够的时间。有什么想法吗？有什么其他信息可以告诉你吗？

更新 -

我只是在做

 def create
    @enhancement = Enhancement.create enhancement_params
    if @enhancement.save
      redirect_to enhancements_path, notice: "Mission Control has receieved your request"
    else
      redirect_to enhancements_path, notice: "Danger! Mission Control could not receive your request!"
    end
  end

这是错误：参数数量错误（1 代表 0）

在 2014-03-20 16:29:38 为 127.0.0.1 开始 POST "/enhancements" -0500 由 EnhancementsController#create 作为 HTML 参数处理：{"utf8"=>"✓", "authenticity_token"=>"pKfKnNGB4CWNSBOOKAe/l6Em+MSV5l+tLS0kDRTCQEc=", "enhancement"=>{"name"=>"哇什么enhancement", "description"=>"这样 enhamcnet \r\n\r\nvery wow"}, "commit"=>"Save Enhancement"} 完成 3ms 内出现 500 内部服务器错误

ArgumentError - 参数数量错误（1 对应 0）：
activerecord-deprecated_finders (1.0.3) lib/active_record/deprecated_finders/base.rb:28:in call' activerecord (4.0.2) lib/active_record/scoping/named.rb:163:inblock （2 级）范围的活动记录（4.0.2） lib/active_record/relation.rb:270:in scoping' activerecord (4.0.2) lib/active_record/scoping/named.rb:163:inblock in scope'
activerecord (4.0.2) lib/active_record/persistence.rb:36:in create' app/controllers/enhancements_controller.rb:12:increate' actionpack (4.0.2) lib/action_controller/metal/implicit_render.rb:4:in send_action' actionpack (4.0.2) lib/abstract_controller/base.rb:189:inprocess_action' 动作包 (4.0.2) lib/action_controller/metal/rendering.rb:10:in process_action' actionpack (4.0.2) lib/abstract_controller/callbacks.rb:18:inblock in process_action'
activesupport (4.0.2) lib/active_support/callbacks.rb:403:in _run__3594477325221698156__process_action__callbacks' activesupport (4.0.2) lib/active_support/callbacks.rb:80:inrun_callbacks'
actionpack (4.0.2) lib/abstract_controller/callbacks.rb:17:in process_action' actionpack (4.0.2) lib/action_controller/metal/rescue.rb:29:inprocess_action'
动作包 (4.0.2) lib/action_controller/metal/instrumentation.rb:31:in block in process_action' activesupport (4.0.2) lib/active_support/notifications.rb:159:inblock in instrument'
主动支持 (4.0.2) lib/active_support/notifications/instrumenter.rb:20:in instrument' activesupport (4.0.2) lib/active_support/notifications.rb:159:ininstrument' actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:30:in process_action' actionpack (4.0.2) lib/action_controller/metal/params_wrapper.rb:245:inprocess_action' 活动记录（4.0.2） lib/active_record/railties/controller_runtime.rb:18:in process_action' actionpack (4.0.2) lib/abstract_controller/base.rb:136:inprocess' 动作包 (4.0.2) lib/abstract_controller/rendering.rb:44:in process' actionpack (4.0.2) lib/action_controller/metal.rb:195:indispatch' actionpack (4.0.2) lib/action_controller/metal/rack_delegation.rb:13:in dispatch' actionpack (4.0.2) lib/action_controller/metal.rb:231:inblock in action' actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:80:in dispatch' actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:48:incall'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:71:in block in call' actionpack (4.0.2) lib/action_dispatch/journey/router.rb:59:incall' actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:680:in call' warden (1.2.3) lib/warden/manager.rb:35:inblock in call'warden (1.2.3) lib/warden/manager.rb:34:in call' rack (1.5.2) lib/rack/etag.rb:23:incall' 机架 (1.5.2) lib/rack/conditionalget.rb:35:in call' rack (1.5.2) lib/rack/head.rb:11:incall' actionpack (4.0.2) lib/action_dispatch/middleware/params_parser.rb:27:in call' actionpack (4.0.2) lib/action_dispatch/middleware/flash.rb:241:incall' 机架 (1.5.2) lib/rack/session/abstract/id.rb:225:in context' rack (1.5.2) lib/rack/session/abstract/id.rb:220:incall'
actionpack (4.0.2) lib/action_dispatch/middleware/cookies.rb:486:in call' activerecord (4.0.2) lib/active_record/query_cache.rb:36:incall'活动记录（4.0.2） lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in call' activerecord (4.0.2) lib/active_record/migration.rb:369:incall' 动作包 (4.0.2) lib/action_dispatch/middleware/callbacks.rb:29:in block in call' activesupport (4.0.2) lib/active_support/callbacks.rb:373:in_run__4163598129264950275__call__callbacks' activesupport (4.0.2) lib/active_support/callbacks.rb:80:in run_callbacks' actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:27:incall'
actionpack (4.0.2) lib/action_dispatch/middleware/reloader.rb:64:in call' actionpack (4.0.2) lib/action_dispatch/middleware/remote_ip.rb:76:incall'
better_errors (1.1.0) lib/better_errors/middleware.rb:84:in protected_app_call' better_errors (1.1.0) lib/better_errors/middleware.rb:79:inbetter_errors_call'
better_errors (1.1.0) lib/better_errors/middleware.rb:56:in call' actionpack (4.0.2) lib/action_dispatch/middleware/debug_exceptions.rb:17:incall'
动作包 (4.0.2) lib/action_dispatch/middleware/show_exceptions.rb:30:in call' railties (4.0.2) lib/rails/rack/logger.rb:38:incall_app' railties (4.0.2) lib/rails/rack/logger.rb:20:in block in call' activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:inblock in tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:25:in tagged' activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:intagged' railties (4.0.2) lib/rails/rack/logger.rb:20:in call' actionpack (4.0.2) lib/action_dispatch/middleware/request_id.rb:21:incall' 机架 (1.5.2) lib/rack/methodoverride.rb:21:in call' rack (1.5.2) lib/rack/runtime.rb:17:incall' activesupport (4.0.2) lib/active_support/cache/strategy/local_cache.rb:83:in call' rack (1.5.2) lib/rack/lock.rb:17:incall' actionpack (4.0.2) lib/action_dispatch/middleware/static.rb:64:in call' rack (1.5.2) lib/rack/sendfile.rb:112:incall' railties (4.0.2) lib/rails/engine.rb:511:in call' railties (4.0.2) lib/rails/application.rb:97:incall' 机架 (1.5.2) lib/rack/lock.rb:17:in call' rack (1.5.2) lib/rack/content_length.rb:14:incall' 机架 (1.5.2) lib/rack/handler/webrick.rb:60:in service' /Users/chris/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/webrick/httpserver.rb:138:inservice'
/Users/chris/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/webrick/httpserver.rb:94:in run' /Users/chris/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/webrick/server.rb:295:inblock in start_thread' `

【问题讨论】：

不确定是否是因为您一直在编辑大量内容以找到解决方案，但是：create（看起来是正确的调用）将在验证通过时创建并保存一个新对象。然后save! 将保存它或在验证失败时引发异常。你可能想打电话给build 然后@enhancement.save 来检查它是否保存好。可能值得先解决这个问题。
你能分享错误堆栈跟踪吗？你到底在哪里得到错误？
更新了更多信息！
嘿，很抱歉撤销它，但它不是设计的。用更多信息更新了主帖

标签： ruby-on-rails activerecord ruby-on-rails-4

【解决方案1】：

尝试：

def create
  @enhancement = current_user.enhancements.build enhancement_params

  if @enhancement.save # without bang method, it throws an exception
    redirect_to enhancements_path, notice: "Mission Control has receieved your request"
  else
    redirect_to enhancements_path, notice: "Danger! Mission Control could not receive your request!"
  end
end

我无法想象哪个方法会在该操作中引发错误，因此您应该检查是否有任何before_filter（或Rails 4 中的before_action）导致错误。

【讨论】：

你是对的。我意识到我没有通过设计配置允许的参数！
啊哈。不是before_action，但那里有类似的事情，我不知道是不是导致了它。谢谢！