From 890f03c3a2119429f31ec48764b5ecb9b62ccbc1 Mon Sep 17 00:00:00 2001
From: Martin Renvoize <martin.renvoize@openfifth.co.uk>
Date: Thu, 26 Mar 2026 16:13:42 +0100
Subject: [PATCH] Bug 42030: (follow-up) Don't diff undefined fields

This patch updates the diff for ADD/CREATE and DELETE logactions to
exclude undefined fields from the diff.

Signed-off-by: Lisette Scheer <lisette@bywatersolutions.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit d0955994472b7d7ce0585fd9320668103396cd5f)
Signed-off-by: Jacob O'Mara <Jacob.omara@openfifth.co.uk>
---
 C4/Log.pm | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/C4/Log.pm b/C4/Log.pm
index 603bc8695a..18e03f8390 100644
--- a/C4/Log.pm
+++ b/C4/Log.pm
@@ -123,13 +123,28 @@ sub logaction {
     if ( $actionname =~ /^(ADD|CREATE)$/ ) {
 
         # Log diff against empty hashref for newly created objects
-        $updated  = $is_object ? $original->unblessed : $original;
+        $updated = $is_object ? $original->unblessed : $original;
+        for my $key ( keys %{$updated} ) {
+
+            if ( defined $updated->{$key} && $updated->{$key} ne '' ) {
+                $updated->{$key} = "$updated->{$key}" if blessed( $updated->{$key} );
+            } else {
+                delete $updated->{$key};
+            }
+        }
         $original = {};
     } elsif ( $actionname eq 'DELETE' ) {
 
         # Log diff for deleted objects against empty hashref
         $original = $is_object ? $original->unblessed : $original;
-        $updated  = {};
+        for my $key ( keys %{$original} ) {
+            if ( defined $original->{$key} && $original->{$key} ne '' ) {
+                $original->{$key} = "$original->{$key}" if blessed( $original->{$key} );
+            } else {
+                delete $original->{$key};
+            }
+        }
+        $updated = {};
     } else {
 
         # Log diff against hashref of pre-modified object if passed in