commit 77dbed048ab6fafe5990ce17095ef1395d2ae6b7
Author: SebastianDiel <sebastian.diel@web.de>
Date:   Sat Oct 17 13:51:38 2015 +0200

    fix

diff --git a/src/entitymanager.cpp b/src/entitymanager.cpp
index 796dbc1..05c5038 100644
--- a/src/entitymanager.cpp
+++ b/src/entitymanager.cpp
@@ -381,9 +381,9 @@ bool EntityManager::hasChanged(QSharedPointer<Entity> &entity) {
                 QString relKey = i.key();
                 QVariant v = entity->getProperty(relKey.remove(relKey.size() - appendix.size(),
                                                                appendix.size()));
-                if (!v.isNull()) {
-                    auto entity = EntityInstanceFactory::castQVariant(v);
-                    if (entity->getProperty(entity->getPrimaryKey()) != i.value()) {
+                if (v.isValid() && !v.isNull()) {
+                    auto e = EntityInstanceFactory::castQVariant(v);
+                    if (e->getProperty(entity->getPrimaryKey()) != i.value()) {
                         changed = true;
                         break;
                     }