raise_named_route_error

# File actionpack/lib/action_controller/routing/route_set.rb, line 426
      def raise_named_route_error(options, named_route, named_route_name)
        diff = named_route.requirements.diff(options)
        unless diff.empty?
          raise RoutingError, "#{named_route_name}_url failed to generate from #{options.inspect}, expected: #{named_route.requirements.inspect}, diff: #{named_route.requirements.diff(options).inspect}"
        else
          required_segments = named_route.segments.select {|seg| (!seg.optional?) && (!seg.is_a?(DividerSegment)) }
          required_keys_or_values = required_segments.map { |seg| seg.key rescue seg.value } # we want either the key or the value from the segment
          raise RoutingError, "#{named_route_name}_url failed to generate from #{options.inspect} - you may have ambiguous routes, or you may need to supply additional parameters for this route.  content_url has the following required parameters: #{required_keys_or_values.inspect} - are they all satisfied?"
        end
      end