check if devise stored the new user and save at repository

app/controllers/registrations_controller.rb

 class RegistrationsController < Devise::RegistrationsController
   after_action :create_user_dependencies, only: :create
 
+  private
+
   def create_user_dependencies
-    # if the user repository is orient db, then create the node in graph
-    # otherwise, nothing happens
-    user_repository.save resource
+    if resource.persisted?
+      user_repository.save resource
+    end
   end
 
   def user_repository

app/repositories/orient_db/user_repository.rb

@@ -8,7 +8,7 @@ module OrientDb
     end
 
     def save(user)
-      connection.query sprintf("INSERT INTO User (title, u_id) VALUES (%s, %d)", user.email, user.id)
+      connection.command sprintf("INSERT INTO User (title, u_id) VALUES ('%s', %d)", user.email, user.id)
     end
 
     def update(params={})