在application_controller的动作，如果我们尝试：
p request.env.to_yaml
我会得到这个错误：
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'
我的问题是：我怎么可以序列request.env到YAML？
其实，我本来是要通过request.env到的delayed_job和发送电子邮件，因为delayed_job的需要序列化对象到数据库我得到这个错误。
问题是，该request.env散列有很多嵌套对象（尤其是模块），它可以不被转换为YAML的。 关键是要删除的散列的那些部分，即不能被转换。
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
我们首先克隆原来的env哈希值，不小心修改。 然后，我们删除了复制这些键，从而导致错误发生。
tmp_env["action_dispatch.routes"]含有内未命名的模块的引用ActionDispatch::Routing::RouteSet对象，这是你的错误的原因。 我们最好将其删除。
tmp_env["action_controller.instance"]包含对原始的基准env -hash（我们不能转换）。 删除它。
最后tmp_env["action_dispatch.remote_ip"]看起来像一个字符串（检查时），但它是一个ActionDispatch::RemoteIp::GetIp实例。 它包含了另一个参照原来的env哈希值。 我们把它转换为字符串，因为我不知道你是否有兴趣在该键后。
此外，您可能会删除更多的键来减少你的YAML输出的大小。 不过，这应该不会引发您所遇到的错误。 一个精简的解决办法是先建立一个空的Hash，只复制你真的需要在你的YAML输出的关键。
红宝石1.9.3和3.2.13轨测试的
这就是我想出的基础上，tessi的例子：
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
通过从代码物理 ，可能听起来有点奇怪，但
request.env.instance_eval "def name; 'some_name'; end"
可能工作。 酷，哼？
