--- a/app/model/Ort.js	Fri Jan 27 13:25:14 2017 +0100
+++ b/app/model/Ort.js	Wed Feb 01 14:52:51 2017 +0100
@@ -25,9 +25,21 @@
     }, {
         name: 'netzbetreiberId'
     }, {
-        name: 'gemId'
+        name: 'gemId',
+        convert: function(v) {
+            if (v === '') {
+                return null;
+            }
+            return v;
+        }
     }, {
-        name: 'staatId'
+        name: 'staatId',
+        convert: function(v) {
+            if (v === '') {
+                return null;
+            }
+            return v;
+        }
     }, {
         name: 'kdaId',
         convert: function(v) {