From ad7a9355a34c8ca56de6388b12fe1b79ed44f126 Mon Sep 17 00:00:00 2001
From: Martin Renvoize <martin.renvoize@openfifth.co.uk>
Date: Thu, 3 Jul 2025 13:55:09 +0100
Subject: [PATCH] Bug 37305: (follow-up) Only add control number subfield when
 defined

The previous commit introduced a bug where the control number subfield 'w'
was being added to the MARC field even when undefined, causing test failures.

This patch adds a condition to only push the control number subfield when
the value is actually defined, matching the pattern used for other subfields
in the method.

Signed-off-by: Martin Renvoize <martin.renvoize@openfifth.co.uk>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 32860c2778bcd39bf2b212829f3102037885814b)
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
---
 Koha/Biblio.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Koha/Biblio.pm b/Koha/Biblio.pm
index 4f0c0bf1f9..45b9b27fc7 100644
--- a/Koha/Biblio.pm
+++ b/Koha/Biblio.pm
@@ -2013,7 +2013,7 @@ sub generate_marc_host_field {
                 $w = '(' . $host_field->data() . ')' . $w;
             }
 
-            push @sfd, ( w => $w );
+            push @sfd, ( w => $w ) if $w;
         }
         $link_field = MARC::Field->new( 773, '0', ' ', @sfd );
     } elsif ( $marcflavour eq 'UNIMARC' ) {