Use Spree::Base as models base class

core/app/models/spree/base.rb

@@ -2,6 +2,7 @@
 
 class Spree::Base < ActiveRecord::Base
   include Spree::Preferences::Preferable
+  include Spree::Core::Permalinks
   serialize :preferences, Hash
 
   include Spree::RansackableAttributes

core/app/models/spree/promotion_code_batch.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Spree
-  class PromotionCodeBatch < ActiveRecord::Base
+  class PromotionCodeBatch < Spree::Base
     class CantProcessStartedBatch < StandardError
     end
 

core/app/models/spree/promotion_rule_role.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Spree
-  class PromotionRuleRole < ActiveRecord::Base
+  class PromotionRuleRole < Spree::Base
     belongs_to :promotion_rule, class_name: 'Spree::PromotionRule', optional: true
     belongs_to :role, class_name: 'Spree::Role', optional: true
   end

core/app/models/spree/shipping_rate_tax.rb

@@ -6,7 +6,7 @@ module Spree
   # @attr [Spree::TaxRate] tax_rate The tax rate used to calculate the tax amount
   # @since 1.3.0
   # @see Spree::Tax::ShippingRateTaxer
-  class ShippingRateTax < ActiveRecord::Base
+  class ShippingRateTax < Spree::Base
     belongs_to :shipping_rate, class_name: "Spree::ShippingRate", optional: true
     belongs_to :tax_rate, class_name: "Spree::TaxRate", optional: true
 

core/db/default/spree/countries.rb

@@ -5,7 +5,7 @@
 # Insert Countries into the spree_countries table, checking to ensure that no
 # duplicates are created, using as few SQL statements as possible (2)
 
-connection = ApplicationRecord.connection
+connection = Spree::Base.connection
 
 country_mapper = ->(country) do
   name            = connection.quote country.name

core/lib/solidus/migrations/promotions_with_code_handlers.rb

@@ -3,7 +3,7 @@
 module Solidus
   module Migrations
     module PromotionWithCodeHandlers
-      class PromotionCode < ActiveRecord::Base
+      class PromotionCode < Spree::Base
         self.table_name = "spree_promotion_codes"
       end
 

core/lib/spree/core/permalinks.rb

@@ -9,7 +9,7 @@ module Permalinks
         class_attribute :permalink_options
       end
 
-      module ClassMethods
+      class_methods do
         def make_permalink(options = {})
           options[:field] ||= :permalink
           self.permalink_options = options
@@ -63,5 +63,3 @@ def save_permalink(permalink_value = to_param)
     end
   end
 end
-
-ActiveRecord::Base.send :include, Spree::Core::Permalinks