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 25 def before begin header = Rack::Accept::MediaType.new env['HTTP_ACCEPT'] rescue RuntimeError => e throw :error, status: 406, headers: error_headers, message: e.message end 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? { |header_value| has_vendor?(header_value) || version?(header_value) } throw :error, status: 406, headers: error_headers, message: 'API vendor or version not found.' end end
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