Rewritten using quasar framework

backend/app/models/application_record.rb

@@ -0,0 +1,3 @@
+class ApplicationRecord < ActiveRecord::Base
+  primary_abstract_class
+end

backend/app/models/user.rb

@@ -0,0 +1,7 @@
+class User < ApplicationRecord
+    has_secure_password
+    validates :email, presence: true, uniqueness: true
+    validates :email, format: { with: URI::MailTo::EMAIL_REGEXP }
+    validates :username, presence: true
+    validates :password, presence: true
+end