1

我刚刚在我的小 Rails 3.2 应用程序上安装了延迟作业。这是我使用它的控制器：

require 'waveform'

class MixesController < ApplicationController
  def index
  end

  def new
    @mix = Mix.new
  end

  def create
    @mix = Mix.new(params[:mix])
    if @mix.save
      options = {
        method: :rms,
        width: 1800,
        height: 280,
        background_color: "#ffffff",
        color: "#3333ff",
        force: true,
        quiet: true
      }

      waveform = "./public/waveforms/#{File.basename(@mix.sound_file.to_s, File.extname(@mix.sound_file.to_s))}.png"
      ::Waveform.new("./public" + @mix.sound_file.to_s, nil).delay.generate(waveform, options)

      flash[:success] = "Mix successfully uploaded"
      redirect_to mix_url(@mix)
    else
      render :new
    end
  end

  def show
    @mix = Mix.find(params[:id])
  end
end

我收到一条错误消息：undefined methodname' for nil:NilClass`，这是完整的堆栈跟踪：

/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:25:in `block in initialize'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `yield'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `default'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `block in initialize'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `yield'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `default'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `block in initialize'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `yield'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `default'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `block in initialize'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `yield'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `default'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:27:in `block in initialize'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `yield'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `default'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:447:in `block in dump_ivars'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `each'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `dump_ivars'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:124:in `visit_Object'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:434:in `block in emit_coder'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:432:in `each'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:432:in `emit_coder'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:417:in `dump_coder'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:100:in `accept'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:66:in `push'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych.rb:242:in `dump'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/core_ext.rb:14:in `psych_to_yaml'
delayed_job (3.0.3) lib/delayed/backend/base.rb:80:in `payload_object='
activerecord (3.2.3) lib/active_record/attribute_assignment.rb:85:in `block in assign_attributes'
activerecord (3.2.3) lib/active_record/attribute_assignment.rb:78:in `each'
activerecord (3.2.3) lib/active_record/attribute_assignment.rb:78:in `assign_attributes'
activerecord (3.2.3) lib/active_record/base.rb:498:in `initialize'
delayed_job (3.0.3) lib/delayed/backend/base.rb:28:in `new'
delayed_job (3.0.3) lib/delayed/backend/base.rb:28:in `enqueue'
delayed_job (3.0.3) lib/delayed/message_sending.rb:13:in `method_missing'
app/controllers/mixes_controller.rb:25:in `create'
actionpack (3.2.3) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.3) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.3) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.3) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.3) lib/active_support/callbacks.rb:414:in `_run__842168672059661955__process_action__4066633601342968686__callbacks'
activesupport (3.2.3) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.3) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.3) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.3) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.3) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.3) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.3) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.3) lib/action_controller/metal/params_wrapper.rb:205:in `process_action'
activerecord (3.2.3) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.3) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.3) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.3) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.3) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.3) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.3) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.3) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.3) lib/journey/router.rb:68:in `block in call'
journey (1.0.3) lib/journey/router.rb:56:in `each'
journey (1.0.3) lib/journey/router.rb:56:in `call'
actionpack (3.2.3) lib/action_dispatch/routing/route_set.rb:600:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.1) lib/rack/etag.rb:23:in `call'
rack (1.4.1) lib/rack/conditionalget.rb:35:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/cookies.rb:338:in `call'
activerecord (3.2.3) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:467:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.3) lib/active_support/callbacks.rb:405:in `_run__647780415925652457__call__1911592835196459847__callbacks'
activesupport (3.2.3) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.3) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.3) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.3) lib/rails/rack/logger.rb:26:in `call_app'
railties (3.2.3) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.3) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.3) lib/rails/engine.rb:479:in `call'
railties (3.2.3) lib/rails/application.rb:220:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/Users/aziz/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

请问有谁知道我为什么会收到这个错误？

4

1 回答 1

1

发生这种情况是因为系统试图将 nil 转换为可以存储在 YAML 中的值并且失败了。

查看您的代码，我希望这是因为您将 nil 对象传递给传递给 Waveform.new 的变量（操作被延迟的方法）。传递给 new 的变量需要存储，直到延迟的作业准备好运行该流程，我希望它们存储为 YAML。

您可以重构 Waveform 以使第二个属性可选（因此不必保留其值）

::Waveform.new("./public" + @mix.sound_file.to_s).delay.generate(waveform, options)

或使用其他东西与 nil 具有相同的含义。例如，传入符号 :none。然后该行变为：

::Waveform.new("./public" + @mix.sound_file.to_s, :none).delay.generate(waveform, options)
于 2013-08-13T09:20:27.380 回答