diff --git a/Models/CalendarMapper.php b/Models/CalendarMapper.php
index 0e63c36..bf50983 100644
--- a/Models/CalendarMapper.php
+++ b/Models/CalendarMapper.php
@@ -111,6 +111,11 @@ class CalendarMapper extends DataMapperAbstract
     {
         try {
             $objId = parent::create($obj, $relations);
+
+            if($objId === null || !is_scalar($objId)) {
+                return $objId;
+            }
+
             $query = new Builder(self::$db);
             $query->prefix(self::$db->getPrefix())
                   ->insert(
diff --git a/Models/EventMapper.php b/Models/EventMapper.php
index 573445b..62806b8 100644
--- a/Models/EventMapper.php
+++ b/Models/EventMapper.php
@@ -106,6 +106,11 @@ class EventMapper extends DataMapperAbstract
     {
         try {
             $objId = parent::create($obj, $relations);
+
+            if($objId === null || !is_scalar($objId)) {
+                return $objId;
+            }
+
             $query = new Builder(self::$db);
 
             $query->prefix(self::$db->getPrefix())
diff --git a/Models/ScheduleMapper.php b/Models/ScheduleMapper.php
index cc416ec..4fd3eac 100644
--- a/Models/ScheduleMapper.php
+++ b/Models/ScheduleMapper.php
@@ -96,6 +96,11 @@ class ScheduleMapper extends DataMapperAbstract
     {
         try {
             $objId = parent::create($obj, $relations);
+
+            if($objId === null || !is_scalar($objId)) {
+                return $objId;
+            }
+
             $query = new Builder(self::$db);
             $query->prefix(self::$db->getPrefix())
                   ->insert(