From 700eea96e6ed6ba48a3460bb2d831dc0a5eb05ca Mon Sep 17 00:00:00 2001
From: Kyle M Hall <kyle@bywatersolutions.com>
Date: Thu, 15 Mar 2012 16:27:07 -0400
Subject: [PATCH] Bug 7722 - Insidious problem with searching

I cannot find the root cause of this issue, but multiple libraries that I am aware of have problems searching on particular search terms ( and never the same terms at the same library ). The error they get when they trigger this problem is:

Tag "" is not a valid tag. at /home/koha/kohaclone/C4/Biblio.pm line 1849

Something somewhere is adding empty keys to C4::Context->marcfromkohafield, I think it may have something to do with the analytics feature that was added.

In the while loop for TransformKohaToMarc, there is a line

next unless my $dtm = $db_to_marc->{''}->{$name};

I don't think it's working.
If I dump $dtm, for each search, I see the dump twice.
It looks like this:
$VAR1 = [
           '952',
           'w'
         ];
 $VAR1 = [];
I think the second time, when it is empty is what's breaking this.
The next never fails because even though it is empty, it is still a valid arrayref.

The solution I have some up with is to skip over the elements where the arrayref is empty.
---
 C4/Biblio.pm |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/C4/Biblio.pm b/C4/Biblio.pm
index 81da91b..021dd99 100644
--- a/C4/Biblio.pm
+++ b/C4/Biblio.pm
@@ -1973,6 +1973,7 @@ sub TransformKohaToMarc {
     my $db_to_marc = C4::Context->marcfromkohafield;
     while ( my ($name, $value) = each %$hash ) {
         next unless my $dtm = $db_to_marc->{''}->{$name};
+        next unless ( scalar( @$dtm ) );
         my ($tag, $letter) = @$dtm;
         foreach my $value ( split(/\s?\|\s?/, $value, -1) ) {
             if ( my $field = $record->field($tag) ) {
-- 
1.7.2.5