From 448f7d1432dc0a0d30afb288e78291b46c3db7cf Mon Sep 17 00:00:00 2001
From: Nick Clemens <nick@bywatersolutions.com>
Date: Wed, 28 Sep 2022 18:53:28 +0000
Subject: [PATCH] Bug 31644: Check if subfield defined, not for truth
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To test:
1 - Define a new MARC Modification template with actions:
        Copy field 600$a to 942$0
2 - Define a new record like:
    LDR 00334nam a22001217a 4500
    003 ff
    005 20201102111604.0
    008 201102b        xxu||||| |||| 00| 0 eng d
    040 _ _ ‡cvsd
    100 1 _ ‡012345‡aKnuth, Donal Ervin‡d1938
    245 _ _ ‡012345‡aThe aty of computer programming‡cDonald E. Knuth
    600 _ 0 ‡042‡aComputer programming‡9462
3 - Modify this record using the template above
4 - Note that entire  field is copied to 942
5 - Apply patch
6 - Now only subfield 0 is copied

Signed-off-by: David Nind <david@davidnind.com>

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 2f61afa9c502874ed98e9cc67f6b99d6365bbf95)
---
 Koha/SimpleMARC.pm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Koha/SimpleMARC.pm b/Koha/SimpleMARC.pm
index 6fd08b1013..5aab1285d7 100644
--- a/Koha/SimpleMARC.pm
+++ b/Koha/SimpleMARC.pm
@@ -92,9 +92,9 @@ sub copy_field {
     if ( ! ( $record && $fromFieldName && $toFieldName ) ) { return; }
 
 
-    if (   not $fromSubfieldName
+    if (   not defined $fromSubfieldName
         or $fromSubfieldName eq ''
-        or not $toSubfieldName
+        or not defined $toSubfieldName
         or $toSubfieldName eq '' ) {
         _copy_move_field(
             {   record        => $record,
-- 
2.39.5