Linking to an engine mounted inside a localized block fails

[robotex82]

When trying to link to an engine, that is mounted inside a localized block, I get following error message:

undefined method `segment_keys' for nil:NilClass

I added a failing test for this situation in my fork in the branch engine-in-localized-block (https://github.com/robotex82/route_translator/tree/engine-in-localized-block).

Can you please help?

Thanks in advance!

Best regards
Roberto

[tagliala]

I've also seen a fix

Do you mind to submit a PR?

[robotex82]

Sorry, I haven't found a fix by now. Should I PR the failing test?

[tagliala]

No, don't worry

Since I don't use the gem this way, I'm asking what is the expected behaviour.

I mean, if I mount an engine in a localized block, what it should happen?

[robotex82]

Mounting works, but when you try to use url_for or a polymorphic route helper on the engine (i.e. blorgh.posts_path) it throws an error (see my first post).

[robotex82]

The error ist thrown in https://github.com/rails/rails/blob/4-2-stable/actionpack/lib/action_dispatch/routing/mapper.rb

In following method:

      def define_generate_prefix(app, name)
        _route = @set.named_routes.get name
        _routes = @set
        app.routes.define_mounted_helper(name)
        app.routes.extend Module.new {
          def optimize_routes_generation?; false; end
          define_method :find_script_name do |options|
            if options.key? :script_name
              super(options)
            else
              prefix_options = options.slice(*_route.segment_keys)
              prefix_options[:relative_url_root] = ''.freeze
              # we must actually delete prefix segment keys to avoid passing them to next url_for
              _route.segment_keys.each { |k| options.delete(k) }
              _routes.url_helpers.send("#{name}_path", prefix_options)
            end
          end
        }
      end

In following line, *_route is nil, and it should not be:

prefix_options = options.slice(*_route.segment_keys)