1 files changed, 14 insertions, 5 deletions
diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index c8716741b0..08f450278d 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -16,7 +16,7 @@ module ActiveRecord
         end
       end
 
-      def target=(record)
+      def inversed_from(record)
         replace_keys(record)
         super
       end
@@ -42,6 +42,10 @@ module ActiveRecord
         update_counters(1)
       end
 
+      def target_changed?
+        owner.saved_change_to_attribute?(reflection.foreign_key)
+      end
+
       private
         def replace(record)
           if record
@@ -53,6 +57,8 @@ module ActiveRecord
             decrement_counters
           end
 
+          replace_keys(record)
+
           self.target = record
         end
 
@@ -77,19 +83,22 @@ module ActiveRecord
         def update_counters_on_replace(record)
           if require_counter_update? && different_target?(record)
             owner.instance_variable_set :@_after_replace_counter_called, true
-            record.increment!(reflection.counter_cache_column)
+            record.increment!(reflection.counter_cache_column, touch: reflection.options[:touch])
             decrement_counters
           end
         end
 
         # Checks whether record is different to the current target, without loading it
         def different_target?(record)
-          record.id != owner._read_attribute(reflection.foreign_key)
+          record._read_attribute(primary_key(record)) != owner._read_attribute(reflection.foreign_key)
         end
 
         def replace_keys(record)
-          owner[reflection.foreign_key] = record ?
-            record._read_attribute(reflection.association_primary_key(record.class)) : nil
+          owner[reflection.foreign_key] = record ? record._read_attribute(primary_key(record)) : nil
+        end
+
+        def primary_key(record)
+          reflection.association_primary_key(record.class)
         end
 
         def foreign_key_present?