Rack Error "Rack::Lint::LintError: Response body must respond to each"

I'm going through the tekpub rack tutorial but when I try to run even a basic program in 开发者_JAVA百科rack i get this error.

ERROR Rack::Lint::LintError: Response body must respond to each
/Users/adam/.rvm/gems/ruby-1.9.3-preview1/gems/rack-1.3.4/lib/rack/lint.rb:19:in     `assert'
/Users/adam/.rvm/gems/ruby-1.9.3-preview1/gems/rack-1.3.4/lib/rack/lint.rb:513:in `each'
/Users/adam/.rvm/gems/ruby-1.9.3-preview1/gems/rack-1.3.4/lib/rack/body_proxy.rb:23:in `method_missing'
/Users/adam/.rvm/gems/ruby-1.9.3-preview1/gems/rack-1.3.4/lib/rack/chunked.rb:23:in `each'
/Users/adam/.rvm/gems/ruby-1.9.3-preview1/gems/rack-1.3.4/lib/rack/handler/webrick.rb:71:in `service'
/Users/adam/.rvm/rubies/ruby-1.9.3-preview1/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/Users/adam/.rvm/rubies/ruby-1.9.3-preview1/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/Users/adam/.rvm/rubies/ruby-1.9.3-preview1/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

This is the program im trying to run:

class EnvironmentOutput

  def call(env)
     ["200",{"Content-Type" => "text/plain"}, "Hello World"]
  end

end

run EnvironmentOutput.new

I'm a beginner programmer so I'm not sure whats going on. Tried google searches but nothing has come up.

Using ruby 1.9.3 Rack 1.1

Thanks

This is a change in Ruby 1.9.2 and, as has been suggested, if you surround your string with ["brackets"] it will turn "Hello World" into an array with a single value. Sounds silly, but that's the deal :).

It used to be that a String in Ruby would respond to each with an iteration of characters. Evidently there have been changes that way.

Perhaps you can try this.

require 'stringio'

class EnvironmentOutput
  def call(env)
   ["200",{"Content-Type" => "text/plain"}, StringIO.new("Hello World")]
  end
end

run EnvironmentOutput.new

According to the rack spec, the body must only yield strings, but must not be a string itself. It specifically states failing to do so will not work in 1.9. What I've done here is wrap the string body in a StringIO instance. StringIO acts like a file handle and returns string output.

since the error is ERROR Rack::Lint::LintError: Response body must respond to each. you get that the "Hello World" being a simple string, doesn't support each. Simple answer to that is just to add the [] to the string, turning it into an array and therefore supporting each.

class EnvironmentOutput
  def call(env)
    ["200",{"Content-Type" => "text/plain"}, ["Hello World"]]
  end
end

run EnvironmentOutput.new

This answer seems to answer your question:

If you check out the rack spec (found here: http://rack.rubyforge.org/doc/SPEC.html) under the body section it says:

The Body must respond to each and must only yield String values. The Body itself should not be an instance of String, as this will break in Ruby 1.9.