gistfile1.rb

 def oauth_required(options = {})
          if scope = options.delete(:scope)
            before_filter options do |controller|
              if controller.oauth.authenticated?
                if !controller.oauth.scope.strip.split.include?(scope)
                  controller.send :head, controller.oauth.no_scope!(scope)
                end
              else
                controller.send :head, controller.oauth.no_access!
              end
            end
          else
            before_filter :oauth_required, options
          end
        end
      end


        # Rejects the request and returns 401 (Unauthorized). You can just
        # return 401, but this also sets the WWW-Authenticate header the right
        # value.
        #
        # @return 401
        def no_access!
          @response["oauth.no_access"] = "true"
          @response.status = 401
        end
        
        # Rejects the request and returns 403 (Forbidden). You can just
        # return 403, but this also sets the WWW-Authenticate header the right
        # value. Indicates which scope the client needs to make this request.
        #
        # @param [String] scope The missing scope, e.g. "read"
        # @return 403
        def no_scope!(scope)
          @response["oauth.no_scope"] = scope.to_s
          #render :json => "[hello!]"  doesn't work
          @response.status = 403
        end