Single database for multiple shops

Use ActsAsTenant as Multi-tenancy for shops

See below files:
- app/controllers/concern/multi_tenancy.rb
- app/models/application_record.rb
- app/models/shop.rb

An initializer can be created to control option in ActsAsTenant.
config/initializers/acts_as_tenant.rb
require 'acts_as_tenant/sidekiq'
ActsAsTenant.configure do |config|
  config.require_tenant = false # true
end

more details: https://github.com/ErwinM/acts_as_tenant

app/models/application_record.rb

@@ -1,3 +1,14 @@
 class ApplicationRecord < ActiveRecord::Base
   self.abstract_class = true
+
+  def self.inherited(subclass)
+    super
+
+    return unless subclass.superclass == self
+    return unless subclass.column_names.include? 'shop_id'
+
+    subclass.class_eval do
+      acts_as_tenant(:shop)
+    end
+  end
 end