Rack::Accept is a suite of tools for Ruby/Rack applications that eases the complexity of building and interpreting the Accept* family of HTTP request headers.
Some features of the library are:
Using RubyGems:
$ sudo gem install rack-accept
From a local copy:
$ git clone git://github.com/mjijackson/rack-accept.git
$ cd rack-accept
$ rake package && sudo rake install
Rack::Accept implements the Rack middleware interface and may be used with any
Rack-based application. Simply insert the Rack::Accept
module in your Rack
middleware pipeline and access the Rack::Accept::Request
object in the
rack-accept.request
environment key, as in the following example.
require 'rack/accept'
use Rack::Accept
app = lambda do |env|
accept = env['rack-accept.request']
response = Rack::Response.new
if accept.media_type?('text/html')
response['Content-Type'] = 'text/html'
response.write "<p>Hello. You accept text/html!</p>"
else
response['Content-Type'] = 'text/plain'
response.write "Apparently you don't accept text/html. Too bad."
end
response.finish
end
run app
Rack::Accept can also construct automatic 406 responses if you set up
the types of media, character sets, encoding, or languages your server is able
to serve ahead of time. If you pass a configuration block to your use
statement it will yield the Rack::Accept::Context
object that is used for that
invocation.
require 'rack/accept'
use(Rack::Accept) do |context|
# We only ever serve content in English or Japanese from this site, so if
# the user doesn't accept either of these we will respond with a 406.
context.languages = %w< en jp >
end
app = ...
run app
Note: You should think carefully before using Rack::Accept in this way. Many user agents are careless about the types of Accept headers they send, and depend on apps not being too picky. Instead of automatically sending a 406, you should probably only send one when absolutely necessary.
Additionally, Rack::Accept may be used outside of a Rack context to provide any Ruby app the ability to construct and interpret Accept headers.
require 'rack/accept'
mtype = Rack::Accept::MediaType.new
mtype.qvalues = { 'text/html' => 1, 'text/*' => 0.8, '*/*' => 0.5 }
mtype.to_s # => "Accept: text/html, text/*;q=0.8, */*;q=0.5"
cset = Rack::Accept::Charset.new('unicode-1-1, iso-8859-5;q=0.8')
cset.best_of(%w< iso-8859-5 unicode-1-1 >) # => "unicode-1-1"
cset.accept?('iso-8859-1') # => true
The very last line in this example may look like a mistake to someone not familiar with the intricacies of the spec, but it's actually correct. It just puts emphasis on the convenience of using this library so you don't have to worry about these kinds of details.
Copyright 2012 Michael Jackson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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