Routing&Engines: fallback on hosting-routes, non-prefixed links?

I'm currently trying to convert an existing non-engine-plugin (for redmine) into an engine: Here I ran into some routing issues: a controller in the plugin uses a layout from the hosting application, the hosting application now tries to render links inside this layout within the context of the plugin's controller, which fails, as the plugin does not define them, only the hosting application does.

the edgeguide on routes( says, qualifying the will solve this issue:

link_to ``"Home"``, main_app.root_path


however, I cannot/do not want to rewrite *all* the links in the hosting application: Is there a way to have rails fall back on the links of the hosting-application, when a route is not found in the plugin?

A somewhat similar problem happens, when I use link_to with an url like:

link_to "My Account", {:controller => "my",:action => :account}

which works fine, when called from the hosting-application(as the my-controller exists there, but get’s prefixed with the plugin’s namespace, when it is called from within a controller inside the plugin, which gives a:

`ActionController::RoutingError (No route matches {:controller=>"redmine_config/my", :action=>"account"}):


as the plugin does not define the my-controller.

figured it out: the solution here is to

  • remove the isolate_namespace from the engine: this allows access to the routes/route-helpers of the hosting app.
  • do not namespace the controller(app/my_controller instead of app/my_plugin/my_controller) you are calling the layout from: otherwise, this namespace gets prefixed