Refactor session_current_user_id in a shared concern (#4936)

app/controllers/application_controller.rb

@@ -1,6 +1,7 @@
 class ApplicationController < ActionController::Base
   protect_from_forgery with: :exception, prepend: true
 
+  include SessionCurrentUser
   include Pundit
 
   def require_http_auth
@@ -18,11 +19,6 @@ class ApplicationController < ActionController::Base
     raise NotAuthorizedError, "Unauthorized"
   end
 
-  def session_current_user_id
-    session["warden.user.user.key"].flatten[0] if session["warden.user.user.key"].present?
-  end
-  helper_method :session_current_user_id
-
   def authenticate_user!
     return if current_user
 

app/controllers/application_metal_controller.rb

@@ -1,10 +1,4 @@
 class ApplicationMetalController < ActionController::Metal
   # Any shared behavior across metal-oriented controllers can go here.
-
-  def session_current_user_id
-    # This method should stay in sync with the ApplicationController equivalent
-    # Could/should be extracted to the appropriate place for ideal code sharing and efficiency
-
-    session["warden.user.user.key"].flatten[0] if session["warden.user.user.key"].present?
-  end
+  include SessionCurrentUser
 end

app/controllers/concerns/session_current_user.rb

@@ -0,0 +1,11 @@
+module SessionCurrentUser
+  extend ActiveSupport::Concern
+
+  # Extracts the current user ID from the session
+  def session_current_user_id
+    return unless session["warden.user.user.key"]
+
+    # the value is in the format [[1], "..."] where 1 is the ID
+    session["warden.user.user.key"].first.first
+  end
+end