From 219c982db7ee6c7c8cc6b20a376589a9f09aa433 Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Sat, 23 Jan 2021 15:14:11 +0000
Subject: [PATCH] Re-implement pre-Rails-5 versions of #implement! and
 #decrement! on Spree::LineItem

Rails 5 introduced some breaking changes to these built-in methods, and the new versions no longer work correctly in relation to decrementing stock with VariantOverrides.
---
 .../concerns/line_item_stock_changes.rb       | 19 +++++++++++++++++++
 app/models/spree/line_item.rb                 |  1 +
 2 files changed, 20 insertions(+)
 create mode 100644 app/models/concerns/line_item_stock_changes.rb

diff --git a/app/models/concerns/line_item_stock_changes.rb b/app/models/concerns/line_item_stock_changes.rb
new file mode 100644
index 0000000000..a61bb21be3
--- /dev/null
+++ b/app/models/concerns/line_item_stock_changes.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# Rails 5 introduced some breaking changes to these built-in methods, and the new versions
+# no longer work correctly in relation to decrementing stock with LineItems / VariantOverrides.
+# The following methods re-instate the pre-Rails-5 versions, which work as expected.
+# https://apidock.com/rails/v4.2.9/ActiveRecord/Persistence/increment%21
+# https://apidock.com/rails/v4.2.9/ActiveRecord/Persistence/decrement%21
+
+module LineItemStockChanges
+  extend ActiveSupport::Concern
+
+  def increment!(attribute, by = 1)
+    increment(attribute, by).update_attribute(attribute, self[attribute])
+  end
+
+  def decrement!(attribute, by = 1)
+    decrement(attribute, by).update_attribute(attribute, self[attribute])
+  end
+end
diff --git a/app/models/spree/line_item.rb b/app/models/spree/line_item.rb
index c2da5814d6..6b502e1bcd 100644
--- a/app/models/spree/line_item.rb
+++ b/app/models/spree/line_item.rb
@@ -6,6 +6,7 @@ require 'variant_units/variant_and_line_item_naming'
 module Spree
   class LineItem < ActiveRecord::Base
     include VariantUnits::VariantAndLineItemNaming
+    include LineItemStockChanges
     include LineItemBasedAdjustmentHandling
 
     belongs_to :order, class_name: "Spree::Order", inverse_of: :line_items