Fix `different_target?` to respect custom primary key counter

1 files changed, 6 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index 775559e224..121592733c 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -86,12 +86,15 @@ module ActiveRecord
 
         # 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?