# HG changeset patch
# Parent 8d5573b704b2867788dd6895503f1871c2976a29

Index: doc-backend/openacademy/course.py
===================================================================
--- doc-backend.orig/openacademy/course.py	2014-08-22 17:01:50.147102793 +0200
+++ doc-backend/openacademy/course.py	2014-08-22 17:01:50.139102793 +0200
@@ -39,3 +39,20 @@
         else:
             self.taken_seats = 100.0 * len(self.attendee_ids) / self.seats
 
+    @api.onchange('seats', 'attendee_ids')
+    def _verify_valid_seats(self):
+        if self.seats < 0:
+            return {
+                'warning': {
+                    'title': "Incorrect 'seats' value",
+                    'message': "The number of available seats may not be negative",
+                },
+            }
+        if self.seats < len(self.attendee_ids):
+            return {
+                'warning': {
+                    'title': "Too many attendees",
+                    'message': "Increase seats or remove excess attendees",
+                },
+            }
+