Devise + LocomotiveCMS - Remember the page I was trying to visit before being asked to log in

I'm trying to add a simple feature to locomotivecms (github). A very simple feature: currently users are redirected to the "main admin hub" (/admin/) after logging in - even if they were trying to edit a different page. I want them to be directed to that page after logging in instead.

It seems a very simple and reasonable thing to add, but after two days trying I've decided to ask for help.

This is what I've found out so far.

This app doesn't use ActiveRecord, but Mongoid (the backend db is MongoDB)
Locomotive doesn't use a simple "User" schema. Authentication is divided into two parts: "accounts" (email, password, name, etc) and "site" (it's a multi-site cms). A "site" has many "memberhips". A membership has one site_id and account_id (and also, a role, but that's not important for this, I think).
Most of the "action" in locomotive is behind the /admin/ route. For example, the login path is /admin/log_in . Most controllers are inside an /admin/ subfolder, too.
I've found this bit in the /admin/sessions_controller that apparently "fixes" the url to be visited after being logged in to the /admin/ root.

Here's the relevant bit:

def after_sign_in_path_for(resource)
  admin_pages_url
end

I'm nearly sure that what I need is this instead:

def after_sign_in_path_for(resource)
  stored_location_for(resource) || admin_pages_url
end

If I have understood Devise's documentation correctly, stored_location_for searches for a value in the session (session['admin_return_to'] in Locomotive's case) to "see if someone wants to go back somewhere". If it's empty, the || ensures a safe path to the admin root.

Unfortunately this doesn't work. It seems that the session variable that I need is never set up. I was assuming that Devise did this kindof automatically.

Must I set the session value myself? If so, where? Or are my assumptions wrong?

Thanks a lot!

Solution

Best solution is updating to the latest version of LocomotiveCMS.