Bug 28960: Explicitly call get_column

Bug 28960: Explicitly call get_column

This patch adds get_column to ensure we are returning a string value of
a field rather than accidentally triggering a relationship accessor.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit c3ef810a546ac35557484e12d7c2ff10c471b62d)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 9dbf469605a3e97e66cb079961da65f7240e0cef)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>