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/kbz_pay.rb

@@ -3,13 +3,13 @@ class KbzPay
   KBZ_PAY = 'KBZPay'
 
   def self.pay(amount, receipt_no, url, key, app_id, code)
-    shop = Shop.first
+    shop = Shop.current_shop
     prefix = shop.shop_code
     receipt_no = "#{prefix}#{receipt_no}"
 
     datetime = DateTime.now.strftime("%d%m%Y%H%M")
     kbz_app_id = app_id
-    kbz_merch_code = code    
+    kbz_merch_code = code
     kbz_api_key = key
     kbz_provider_url = "#{url}/precreate"
 
@@ -58,17 +58,17 @@ class KbzPay
       # Rails.logger.debug result['Response']
       return false, result['Response']
     end
-    
+
 	end
 
   def self.query(receipt_no, current_user, url, key, app_id, code)
-    shop = Shop.first
+    shop = Shop.current_shop
     prefix = shop.shop_code
     receipt_no = "#{prefix}#{receipt_no}"
     amount = 0
     datetime = DateTime.now.strftime("%d%m%Y%H%M")
     kbz_app_id = app_id
-    kbz_merch_code = code    
+    kbz_merch_code = code
     kbz_api_key = key
     kbz_provider_url = "#{url}/queryorder"
 
@@ -122,7 +122,7 @@ class KbzPay
 
         # return true, "successfully paid by KBZ PAY"
       elsif result['Response']['trade_status'] == "PAY_FAILED"
-          
+
         # return false, "pay failed by KBZ PAY"
       elsif result['Response']['trade_status'] == "WAIT_PAY"
         # return false , "Waiting to pay by KBZ PAY"
@@ -135,4 +135,4 @@ class KbzPay
     return amount
   end
 
-end
+end