From d1b26132d994985617cef6485205ff156941f7e4 Mon Sep 17 00:00:00 2001
From: Jordan Dukart <jordan@discoverygarden.ca>
Date: Wed, 25 Sep 2013 14:43:40 +0000
Subject: [PATCH] Check to see if function exists before calling it.

---
 includes/derivatives.inc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/includes/derivatives.inc b/includes/derivatives.inc
index c66944b1..8a6627e5 100644
--- a/includes/derivatives.inc
+++ b/includes/derivatives.inc
@@ -60,9 +60,14 @@ function islandora_do_derivatives(AbstractObject $object, array $options) {
       require_once $hook['file'];
     }
     foreach ($hook['function'] as $function) {
-      $logging = call_user_func($function, $object, $options['force']);
-      if (!empty($logging)) {
-        $results[] = $logging;
+      if (function_exists($function)) {
+        $logging = call_user_func($function, $object, $options['force']);
+        if (!empty($logging)) {
+          $results[] = $logging;
+        }
+      }
+      else {
+        watchdog('islandora', 'Unable to call derivative function @function as it was not found!', array('@function' => $function), WATCHDOG_ERROR);
       }
     }
   }