email validation

app/models/account.rb

@@ -5,5 +5,5 @@ class Account < ApplicationRecord
   validates :username, presence: true
   validates :password, presence: true
   validates :home_folder, presence: true
-  validates :contact_email, presence: true
+  validates :contact_email, presence: true, email_format: true
 end

app/validators/email_format_validator.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+class EmailFormatValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    # EMAIL regex test
+    # (comma seperated) [any word combo] AT [any word combo] DOT [2 or more]
+    # me@no.yes.x == invalid
+    # some.thing+two@sub.domain.name == valid
+    results = value.to_s.split(',').map do |v|
+      (v.strip =~ /^([\w\.%\+\-]+)@([\w\-]+\.)+([\w]{2,})$/i) || v.strip.blank?
+    end
+    record.errors[attribute] << (options[:message] || "is not formatted properly") if results.include?(false)
+  end
+end