From ecd6964fd8bd2ca38efb528e15c8fd309937d07f Mon Sep 17 00:00:00 2001
From: Asher Cerka <83976948+ACerka-Springbuk@users.noreply.github.com>
Date: Mon, 24 Jul 2023 12:29:58 -0400
Subject: [PATCH] APP-3029 Fixes prune duplicates. All records with a nil
 primary key get their primary key replaced by a new object, which will never
 compare true to anything else. (#28)

---
 lib/active_record/merge_all.rb | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/active_record/merge_all.rb b/lib/active_record/merge_all.rb
index 634d40cc..352b9cb3 100644
--- a/lib/active_record/merge_all.rb
+++ b/lib/active_record/merge_all.rb
@@ -80,7 +80,10 @@ def do_prune_duplicates
       end
       @merges = merges.reverse
       merges.uniq! do |merge|
-        primary_keys.map { |key| merge[key] }
+        # Map the primary keys to determine uniqueness. If a primary key is nil, return a new empty object to
+        # guarantee a unique value. We don't ever want to throw out records that have a nil primary key as these are
+        # new records.
+        primary_keys.map { |key| merge[key].nil? ? Object.new : merge[key] }
       end
       merges.reverse!
     end