YAML - TypeError：無法轉儲匿名模塊

Question

在application_controller的一個動作中，如果我們嘗試：

p request.env.to_yaml

我會收到這個錯誤：

    TypeError: can't dump anonymous module: #<Module:0x007fee26e34ad8>
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:267:in `visit_Module'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:447:in `block in dump_ivars'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `each'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `dump_ivars'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:124:in `visit_Object'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:447:in `block in dump_ivars'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `each'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:445:in `dump_ivars'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:124:in `visit_Object'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:292:in `block in visit_Hash'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:290:in `each'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:290:in `visit_Hash'
    from /Users/twer/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb:102:in `accept'

我的問題是：如何將request.env序列化為yaml？

實際上，我應該將request.env傳遞給delayed_job並發送電子郵件，我收到此錯誤，因為delayed_job需要將對象序列化為DB。

Answer 1

問題是，request.env哈希有很多嵌套對象（尤其是模塊），無法轉換為yaml。 訣竅是刪除無法轉換的哈希部分。

tmp_env = request.env.clone
tmp_env.delete "action_dispatch.routes"
tmp_env.delete "action_controller.instance"
tmp_env["action_dispatch.remote_ip"] = tmp_env["action_dispatch.remote_ip"].to_s 
p tmp_env.to_yaml # now it works

我們首先克隆原始的env哈希，以免意外修改它。 然后我們從我們的副本中刪除這些鍵，這會導致錯誤。

tmp_env["action_dispatch.routes"]包含對ActionDispatch::Routing::RouteSet對象中未命名模塊的引用，這是導致錯誤的原因。 我們最好刪除它。

tmp_env["action_controller.instance"]包含對原始env -hash的引用（我們無法轉換）。 刪除它。

最后tmp_env["action_dispatch.remote_ip"]看起來像一個字符串（在檢查它時），但它是一個ActionDispatch::RemoteIp::GetIp實例。 它包含對原始env哈希的另一個引用。 我們將其轉換為字符串，因為我不知道您以后是否對該密鑰感興趣。

此外，您可以刪除更多的鍵來減少您的yaml輸出的大小。 但是，這應該可以工作而不會拋出您遇到的錯誤。 更精簡的解決方案是從空Hash開始，只復制您在yaml輸出中真正需要的鍵。

用ruby 1.9.3和rails 3.2.13測試

Answer 2

基於tessi的例子，這就是我想出的：

module RequestSerializationHelper
  ::SerializableRequest = Struct.new(
    :env,
    :filtered_parameters,
    :fullpath,
    :headers,
    :request_method,
    :remote_ip
  )

  ## From http://stackoverflow.com/questions/7604153/rails-2-3-14-how-to-serialise-an-actioncontrollerrequest-object
  ## with additional modifications

  # build a serializable Struct that out of the given request object, which looks like a real request
  def make_request_serializable(request)
    serializable_request = ::SerializableRequest.new
    serializable_request.env = request.env.clone
    serializable_request.filtered_parameters = request.filtered_parameters.clone if request.respond_to? :filtered_parameters
    serializable_request.fullpath = request.fullpath
    serializable_request.headers = request.respond_to?(:headers) ? request.headers.clone : {}
    serializable_request.request_method = request.request_method

    delete_identified_unserializable_values(serializable_request.env)
    delete_identified_unserializable_values(serializable_request.headers)

    # Some jobs want this, so set it after it's been converted to a string in the env
    serializable_request.remote_ip = serializable_request.env["action_dispatch.remote_ip"]

    # automatically delete anything left that's non-serializable.  If we end up deleting
    # too much and breaking something, here's where to debug it based on info in warning
    delete_unidentified_unserializable_values :env, serializable_request.env
    delete_unidentified_unserializable_values :headers, serializable_request.headers

    serializable_request
  end

  def delete_identified_unserializable_values(hash)
    hash.delete "async.callback"
    hash.delete "action_dispatch.backtrace_cleaner"
    hash.delete "action_dispatch.cookies"
    hash.delete "action_dispatch.request.accepts"
    hash.delete "action_dispatch.routes"
    hash.delete "action_dispatch.logger"
    hash.delete "action_controller.instance"
    hash.delete "rack.input"
    hash.delete "rack.errors"
    hash.delete "rack.session"
    hash.delete "rack.session.options"
    hash["action_dispatch.remote_ip"] = hash["action_dispatch.remote_ip"].to_s
    hash.delete "warden"
    hash.delete_if { |key, _| key =~ /^rack-cache/ }
  end

  private

  def delete_unidentified_unserializable_values(hash_name, hash)
    hash.each do |key, value|
      begin
        serialized = value.to_yaml
        YAML.load(serialized)
      rescue => e
        warning = "RequestSerializationHelper: Automatically removing un(re)serializable entry in " +
          "'#{hash_name}' for key '#{key}' and value '#{value}'.  Exception was: '#{e}'"
        Rails.logger.warn(warning)
        hash.delete key
      end
    end
  end
end

Answer 3

通過物理代碼，可能聽起來有點奇怪，但是

request.env.instance_eval "def name; 'some_name'; end"

可能有用。 很酷，哼哼？