Class: Twirp::Rails::Rack::ConditionalPost

Inherits:
Rack::ConditionalGet
  • Object
show all
Defined in:
lib/twirp/rails/rack/conditional_post.rb

Overview

Middleware that enables conditional POST using If-None-Match and If-Modified-Since. The application should set either or both of the Last-Modified or Etag response headers according to RFC 2616. When either of the conditions is met, the response body is set to be zero length and the response status is set to 304 Not Modified.

Applications that defer response body generation until the body’s each message is received will avoid response body generation completely when a conditional POST matches.

Based on Rack::ConditionalGet

Twirp requests are, be design, always POST. We want the logic of Rack::ConditionalGet but applied to POSTs.

Not all Twirp calls are idemtpotent, so it is left up to the client to know when 304 Not Modified responses are desirable, and send the appropriate header(s).

Instance Method Summary collapse

Instance Method Details

#call(env) ⇒ Object

Return empty 304 response if the response has not been modified since the last request.



30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
 
# File 'lib/twirp/rails/rack/conditional_post.rb', line 30

def call(env)
  case env[::Rack::REQUEST_METHOD]
  when "POST"
    status, headers, body = response = @app.call(env)
    # Rack 3 settles on only allowing lowercase headers
    if ::Rack.release < "3.0"
      headers = ::Rack::Utils::HeaderHash[headers]
    end

    if status == 200 && fresh?(env, headers)
      response[0] = 304
      headers.delete(::Rack::CONTENT_TYPE)
      headers.delete(::Rack::CONTENT_LENGTH)
      response[2] = ::Rack::BodyProxy.new([]) do
        body.close if body.respond_to?(:close)
      end
    end
    response
  else
    @app.call(env)
  end
end