1 files changed, 22 insertions, 7 deletions
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index 11c63591e3..a24b4b7839 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -1,12 +1,18 @@
 require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/module/attribute_accessors'
 
 module ActiveRecord
+  ActiveSupport.on_load(:active_record_config) do
+    mattr_accessor :partial_updates, instance_accessor: false
+    self.partial_updates = true
+  end
+
   module AttributeMethods
     module Dirty
       extend ActiveSupport::Concern
+
       include ActiveModel::Dirty
-      include AttributeMethods::Write
 
       included do
         if self < ::ActiveRecord::Timestamp
@@ -14,7 +20,6 @@ module ActiveRecord
         end
 
         config_attribute :partial_updates
-        self.partial_updates = true
       end
 
       # Attempts to +save+ the record and clears changed attributes if successful.
@@ -72,11 +77,8 @@ module ActiveRecord
 
       def _field_changed?(attr, old, value)
         if column = column_for_attribute(attr)
-          if column.number? && column.null && (old.nil? || old == 0) && value.blank?
-            # For nullable numeric columns, NULL gets stored in database for blank (i.e. '') values.
-            # Hence we don't record it as a change if the value changes from nil to ''.
-            # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
-            # be typecast back to 0 (''.to_i => 0)
+          if column.number? && (changes_from_nil_to_empty_string?(column, old, value) ||
+                                changes_from_zero_to_string?(old, value))
             value = nil
           else
             value = column.type_cast(value)
@@ -85,6 +87,19 @@ module ActiveRecord
 
         old != value
       end
+
+      def changes_from_nil_to_empty_string?(column, old, value)
+        # For nullable numeric columns, NULL gets stored in database for blank (i.e. '') values.
+        # Hence we don't record it as a change if the value changes from nil to ''.
+        # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
+        # be typecast back to 0 (''.to_i => 0)
+        column.null && (old.nil? || old == 0) && value.blank?
+      end
+
+      def changes_from_zero_to_string?(old, value)
+        # For columns with old 0 and value non-empty string
+        old == 0 && value.present? && value != '0'
+      end
     end
   end
 end