serializer stuff

app/services/join_request.rb

@@ -5,6 +5,10 @@ class JoinRequest
   end
   alias _id id
 
+  def list_id
+    list.try(:id)
+  end
+
   def initialize(user: nil, list: nil, created_at: Time.now, updated_at: Time.now)
     @user, @list, @created_at, @updated_at = [user, list, created_at, updated_at]
   end