lib/grape/middleware/versioner/accept_version_header.rb
# frozen_string_literal: true
require 'grape/middleware/base'
module Grape
module Middleware
module Versioner
# This middleware sets various version related rack environment variables
# based on the HTTP Accept-Version header
#
# Example: For request header
# Accept-Version: v1
#
# The following rack env variables are set:
#
# env['api.version'] => 'v1'
#
# If version does not match this route, then a 406 is raised with
# X-Cascade header to alert Grape::Router to attempt the next matched
# route.
class AcceptVersionHeader < Base
def before
potential_version = (env[Grape::Http::Headers::HTTP_ACCEPT_VERSION] || '').strip
if strict? && potential_version.empty?
# If no Accept-Version header:
throw :error, status: 406, headers: error_headers, message: 'Accept-Version header must be set.'
end
return if potential_version.empty?
# If the requested version is not supported:
throw :error, status: 406, headers: error_headers, message: 'The requested version is not supported.' unless versions.any? { |v| v.to_s == potential_version }
env[Grape::Env::API_VERSION] = potential_version
end
private
def versions
options[:versions] || []
end
def strict?
options[:version_options] && options[:version_options][:strict]
end
# By default those errors contain an `X-Cascade` header set to `pass`, which allows nesting and stacking
# of routes (see Grape::Router) for more information). To prevent
# this behavior, and not add the `X-Cascade` header, one can set the `:cascade` option to `false`.
def cascade?
if options[:version_options]&.key?(:cascade)
options[:version_options][:cascade]
else
true
end
end
def error_headers
cascade? ? { Grape::Http::Headers::X_CASCADE => 'pass' } : {}
end
end
end
end
end