Strips the extension from the requested path (env['PATH_INFO']), casts it to media type, and prepends it to env['HTTP_ACCEPT']. This allows dealing with path information separately from format information, which are often different concerns.

This is especially useful when dealing with routes as it allows a resource to always point to the same action independently of the requested format.

gem install rack-abstract-format

require 'rack'
require 'rack/abstract_format'
use Rack::AbstractFormat
run app

The request:

GET /path/resource.xml
Accept: text/html

will become:

GET /path/resource
env['HTTP_ACCEPT'] #=> 'application/xml,text/html'

AbstractFormat also accepts an optional argument, used to set the default format that should be assumed when none is specified on the URL:

use Rack::AbstractFormat, 'text/html'
#=> GET /path/resource      # requested
#=> GET /path/resource.html # assumed

The abstracted media type can then be easily retrieved with the Rack::AcceptMediaTypes convenience middleware, which parses env['HTTP_ACCEPT'].

request.accept_media_types          #=> ['application/xml', 'text/html']
request.accept_media_types.prefered #=>  'application/xml'

• rack-accept-media-types
• simple_router
• rack-respond_to

• code: https://github.com/mynyml/rack-abstract-format
• docs: https://rdoc.info/projects/mynyml/rack-abstract-format
• wiki: https://wiki.github.com/mynyml/rack-abstract-format
• bugs: https://github.com/mynyml/rack-abstract-format/issues