This middleware sets various version related rack environment variables based on the HTTP Accept header with the pattern: application/vnd.:vendor-:version+:format
Example: For request header
Accept: application/vnd.mycompany-v1+json
The following rack env variables are set:
env['api.type'] => 'application' env['api.subtype'] => 'vnd.mycompany-v1+json' env['api.vendor] => 'mycompany' env['api.version] => 'v1' env['api.format] => 'format'
If version does not match this route, then a 406 is raised with X-Cascade header to alert Rack::Mount to attempt the next matched route.
# File lib/grape/middleware/versioner/header.rb, line 26 def before header = Rack::Accept::MediaType.new env['HTTP_ACCEPT'] if strict? # If no Accept header: if header.qvalues.empty? throw :error, :status => 406, :headers => error_headers, :message => 'Accept header must be set.' end # Remove any acceptable content types with ranges. header.qvalues.reject! do |media_type,_| Rack::Accept::Header.parse_media_type(media_type).find{|s| s == '*'} end # If all Accept headers included a range: if header.qvalues.empty? throw :error, :status => 406, :headers => error_headers, :message => 'Accept header must not contain ranges ("*").' end end media_type = header.best_of available_media_types if media_type type, subtype = Rack::Accept::Header.parse_media_type media_type env['api.type'] = type env['api.subtype'] = subtype if /\Avnd\.([a-z0-9*.]+)(?:-([a-z0-9*\-.]+))?(?:\+([a-z0-9*\-.+]+))?\z/ =~ subtype env['api.vendor'] = $1 env['api.version'] = $2 env['api.format'] = $3 # weird that Grape::Middleware::Formatter also does this end # If none of the available content types are acceptable: elsif strict? throw :error, :status => 406, :headers => error_headers, :message => '406 Not Acceptable' # If all acceptable content types specify a vendor or version that doesn't exist: elsif header.values.all?{ |media_type| has_vendor?(media_type) || has_version?(media_type)} throw :error, :status => 406, :headers => error_headers, :message => 'API vendor or version not found.' end end
# File lib/grape/middleware/versioner/header.rb, line 67 def available_media_types available_media_types = [] content_types.each do |extension,media_type| versions.reverse.each do |version| available_media_types += ["application/vnd.#{vendor}-#{version}+#{extension}", "application/vnd.#{vendor}-#{version}"] end available_media_types << "application/vnd.#{vendor}+#{extension}" end available_media_types << "application/vnd.#{vendor}" content_types.each do |_,media_type| available_media_types << media_type end available_media_types = available_media_types.flatten end
By default those errors contain an `X-Cascade` header set to `pass`, which allows nesting and stacking of routes (see [Rack::Mount](github.com/josh/rack-mount) for more information). To prevent this behavior, and not add the `X-Cascade` header, one can set the `:cascade` option to `false`.
# File lib/grape/middleware/versioner/header.rb, line 101 def cascade? options[:version_options] && options[:version_options].has_key?(:cascade) ? !! options[:version_options][:cascade] : true end
# File lib/grape/middleware/versioner/header.rb, line 107 def error_headers cascade? ? { 'X-Cascade' => 'pass' } : {} end
@param [String] media_type a content type @return [Boolean] whether the content type sets a vendor
# File lib/grape/middleware/versioner/header.rb, line 113 def has_vendor?(media_type) type, subtype = Rack::Accept::Header.parse_media_type media_type subtype[/\Avnd\.[a-z0-9*.]+/] end
@param [String] media_type a content type @return [Boolean] whether the content type sets an API version
# File lib/grape/middleware/versioner/header.rb, line 120 def has_version?(media_type) type, subtype = Rack::Accept::Header.parse_media_type media_type subtype[/\Avnd\.[a-z0-9*.]+-[a-z0-9*\-.]+/] end
# File lib/grape/middleware/versioner/header.rb, line 94 def strict? options[:version_options] && options[:version_options][:strict] end
# File lib/grape/middleware/versioner/header.rb, line 90 def vendor options[:version_options] && options[:version_options][:vendor] end
# File lib/grape/middleware/versioner/header.rb, line 86 def versions options[:versions] || [] end