--- a/server/src/app/Repositories/RdfDocumentRepository.php	Thu Feb 09 17:22:58 2017 +0100
+++ b/server/src/app/Repositories/RdfDocumentRepository.php	Fri Feb 10 12:03:12 2017 +0100
@@ -96,7 +96,7 @@
 
     private function getResGraph($doc) {
 
-        if(empty((array)$doc)) {
+        if(empty((array)$doc) || !array_key_exists('uri', (array)$doc)) {
             return null;
         }