Question

For some reason, in a Sinatra “after” filter I can’t seem to access the current status code

require 'rubygems'
require 'sinatra'

after do
  puts "After hook with code: #{response.status}"
end

get '/hi' do
  halt(401, "wtf?")
end

When running curl 127.0.0.1:4567/hi, it results in:

After hook for code: 200

Answer 1

It’s basically a function of how the methods are implemented in Sinatra. The methods we need to pay attention to are call!, invoke and dispatch!, all methods in Sinatra::Base (as of v1.3.2).

call! is the top level method, and in there, it calls the following line of code:

invoke { dispatch! }

Now, invoke looks like this:

def invoke
  res = catch(:halt) { yield }
  res = [res] if Fixnum === res or String === res
  if Array === res and Fixnum === res.first
    status(res.shift)
    body(res.pop)
    headers(*res)
  elsif res.respond_to? :each
    body res
  end
end

It actually sets the response code on the basis of the thing you throw with :halt. And dispatch! looks like:

def dispatch!
  static! if settings.static? && (request.get? || request.head?)
  filter! :before
  route!
rescue ::Exception => boom
  handle_exception!(boom)
ensure
  filter! :after unless env['sinatra.static_file']
end

See that ensure block? That gets run as the :halt symbol that has been thrown sails up the stack trace. Crucially, this is before the status setting code is run.