使用OmniAuth for Facebook与Sinatra和Ruby 1.9.3。在auth过程的后期阶段，未打开IO以读取错误。在网上还没有看到太多关于此的内容。如果您需要更多信息，请告诉我。
失败的MultiJson线：
get '/auth/failure' do
content_type 'application/json'
MultiJson.encode(request.env)
end
错误：
/ auth / facebook / callback的IOError未打开以读取文件：encoding.rb location：每行：256
详细错误日志：
== Sinatra/1.4.4 has taken the stage on 4567 for development with backup from Thin
Thin web server (v1.6.1 codename Death Proof)
Maximum connections set to 1024
Listening on localhost:4567, CTRL+C to stop
SECURITY WARNING: No secret option provided to Rack::Session::Cookie.
This poses a security threat. It is strongly recommended that you
provide a secret to prevent exploits that may be possible from crafted
cookies. This will not be supported in future versions of Rack, and
future versions will even invalidate your existing user cookies.
Called from: /Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/builder.rb:86:in `new'.
127.0.0.1 - - [08/Dec/2013 18:34:03] "GET / HTTP/1.1" 302 - 0.0025
I, [2013-12-08T18:34:03.828713 #927] INFO -- omniauth: (facebook) Request phase initiated.
127.0.0.1 - - [08/Dec/2013 18:34:03] "GET /auth/facebook HTTP/1.1" 302 203 0.0049
I, [2013-12-08T18:34:04.278981 #927] INFO -- omniauth: (facebook) Callback phase initiated.
IOError - not opened for reading:
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:256:in `each'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:256:in `to_a'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:256:in `as_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:58:in `block in as_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:81:in `check_for_circular_references'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:57:in `as_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:296:in `block in as_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:296:in `each'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:296:in `map'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:296:in `as_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:50:in `block in encode'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:81:in `check_for_circular_references'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:49:in `encode'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/json/encoding.rb:34:in `encode'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.1/lib/active_support/core_ext/object/to_json.rb:16:in `to_json'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/multi_json-1.8.2/lib/multi_json/adapters/json_common.rb:21:in `dump'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/multi_json-1.8.2/lib/multi_json/adapter.rb:24:in `dump'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/multi_json-1.8.2/lib/multi_json.rb:137:in `dump'
app.rb:87:in `block in <main>'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1593:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1593:in `block in compile!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:957:in `[]'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:957:in `block (3 levels) in route!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:976:in `route_eval'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:957:in `block (2 levels) in route!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:997:in `block in process_route'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:995:in `catch'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:995:in `process_route'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:955:in `block in route!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:954:in `each'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:954:in `route!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1067:in `block in dispatch!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `block in invoke'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `catch'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `invoke'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1064:in `dispatch!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:889:in `block in call!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `block in invoke'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `catch'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1049:in `invoke'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:889:in `call!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:877:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/strategy.rb:401:in `call_app!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/strategy.rb:363:in `callback_phase'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-oauth2-1.0.3/lib/omniauth/strategies/oauth2.rb:65:in `callback_phase'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/strategy.rb:226:in `callback_call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/strategy.rb:182:in `call!'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/strategy.rb:164:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/omniauth-1.1.4/lib/omniauth/builder.rb:49:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/session/abstract/id.rb:225:in `context'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/session/abstract/id.rb:220:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-protection-1.5.1/lib/rack/protection/xss_header.rb:18:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-protection-1.5.1/lib/rack/protection/path_traversal.rb:16:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-protection-1.5.1/lib/rack/protection/json_csrf.rb:18:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-protection-1.5.1/lib/rack/protection/base.rb:50:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-protection-1.5.1/lib/rack/protection/base.rb:50:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/logger.rb:15:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/commonlogger.rb:33:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:217:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:210:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/head.rb:11:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.5.2/lib/rack/methodoverride.rb:21:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/show_exceptions.rb:21:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:180:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:2004:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1469:in `block in call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1778:in `synchronize'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/sinatra-1.4.4/lib/sinatra/base.rb:1469:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/thin-1.6.1/lib/thin/connection.rb:82:in `block in pre_process'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/thin-1.6.1/lib/thin/connection.rb:80:in `catch'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/thin-1.6.1/lib/thin/connection.rb:80:in `pre_process'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/eventmachine-1.0.3/lib/eventmachine.rb:1037:in `call'
/Users/philhudson/.rvm/gems/ruby-1.9.3-p448/gems/eventmachine-1.0.3/lib/eventmachine.rb:1037:in `block in spawn_threadpool'
事实证明，创业板冲突是个问题。我用an indirectly related question that used Rails instead的代码解决了这个问题。请看下面：
#fix for JSON gem/activesupport bug. More info: http://stackoverflow.com/questions/683989/how-do-you-deal-with-the-conflict-between-activesupportjson-and-the-json-gem
if defined?(ActiveSupport::JSON)
[Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass].each do |klass|
klass.class_eval do
def to_json(*args)
super(args)
end
def as_json(*args)
super(args)
end
end
end
end