diff --git a/includes/model/AngelType_model.php b/includes/model/AngelType_model.php
index 642d3d70..2dff7019 100644
--- a/includes/model/AngelType_model.php
+++ b/includes/model/AngelType_model.php
@@ -225,12 +225,14 @@ function AngelType_ids()
  * Returns angelType by id.
  *
  * @param int $angeltype_id angelType ID
- * @return array
+ * @return array|null
  */
 function AngelType($angeltype_id)
 {
-    return DB::selectOne(
+    $angelType = DB::selectOne(
         'SELECT * FROM `AngelTypes` WHERE `id`=?',
         [$angeltype_id]
     );
+
+    return empty($angelType) ? null : $angelType;
 }
diff --git a/includes/model/EventConfig_model.php b/includes/model/EventConfig_model.php
index 6d782ec4..766a5849 100644
--- a/includes/model/EventConfig_model.php
+++ b/includes/model/EventConfig_model.php
@@ -5,11 +5,13 @@ use Engelsystem\Database\DB;
 /**
  * Get event config.
  *
- * @return array
+ * @return array|null
  */
 function EventConfig()
 {
-    return DB::selectOne('SELECT * FROM `EventConfig` LIMIT 1');
+    $config = DB::selectOne('SELECT * FROM `EventConfig` LIMIT 1');
+
+    return empty($config) ? null : $config;
 }
 
 /**
diff --git a/includes/model/Message_model.php b/includes/model/Message_model.php
index 9bd7d6ef..3f66f74a 100644
--- a/includes/model/Message_model.php
+++ b/includes/model/Message_model.php
@@ -16,11 +16,13 @@ function Message_ids()
  * Returns message by id.
  *
  * @param int $message_id message ID
- * @return array
+ * @return array|null
  */
 function Message($message_id)
 {
-    return DB::selectOne('SELECT * FROM `Messages` WHERE `id`=? LIMIT 1', [$message_id]);
+    $message = DB::selectOne('SELECT * FROM `Messages` WHERE `id`=? LIMIT 1', [$message_id]);
+
+    return empty($message) ? null : $message;
 }
 
 /**
diff --git a/includes/model/Room_model.php b/includes/model/Room_model.php
index 36a375aa..b29f68fe 100644
--- a/includes/model/Room_model.php
+++ b/includes/model/Room_model.php
@@ -148,14 +148,16 @@ function Room_update($room_id, $name, $from_frab, $map_url, $description)
  * Returns room by id.
  *
  * @param int $room_id RID
- * @return array
+ * @return array|null
  */
 function Room($room_id)
 {
-    return DB::selectOne('
+    $room = DB::selectOne('
         SELECT *
         FROM `Room`
         WHERE `RID` = ?', [
         $room_id
     ]);
+
+    return empty($room) ? null : $room;
 }
diff --git a/includes/model/ShiftEntry_model.php b/includes/model/ShiftEntry_model.php
index 02eace1e..ebf600f3 100644
--- a/includes/model/ShiftEntry_model.php
+++ b/includes/model/ShiftEntry_model.php
@@ -134,11 +134,13 @@ function ShiftEntry_update($shift_entry)
  * Get a shift entry.
  *
  * @param int $shift_entry_id
- * @return array
+ * @return array|null
  */
 function ShiftEntry($shift_entry_id)
 {
-    return DB::selectOne('SELECT * FROM `ShiftEntry` WHERE `id` = ?', [$shift_entry_id]);
+    $shiftEntry = DB::selectOne('SELECT * FROM `ShiftEntry` WHERE `id` = ?', [$shift_entry_id]);
+
+    return empty($shiftEntry) ? null : $shiftEntry;
 }
 
 /**
diff --git a/includes/model/ShiftTypes_model.php b/includes/model/ShiftTypes_model.php
index 0e8ef3a4..599810be 100644
--- a/includes/model/ShiftTypes_model.php
+++ b/includes/model/ShiftTypes_model.php
@@ -66,11 +66,13 @@ function ShiftType_create($name, $angeltype_id, $description)
  * Get a shift type by id.
  *
  * @param int $shifttype_id
- * @return array
+ * @return array|null
  */
 function ShiftType($shifttype_id)
 {
-    return DB::selectOne('SELECT * FROM `ShiftTypes` WHERE `id`=?', [$shifttype_id]);
+    $shiftType = DB::selectOne('SELECT * FROM `ShiftTypes` WHERE `id`=?', [$shifttype_id]);
+
+    return empty($shiftType) ? null : $shiftType;
 }
 
 /**
diff --git a/includes/model/Shifts_model.php b/includes/model/Shifts_model.php
index 5719a8e1..94513ff3 100644
--- a/includes/model/Shifts_model.php
+++ b/includes/model/Shifts_model.php
@@ -552,7 +552,7 @@ function Shift_update($shift)
  * Update a shift by its external id.
  *
  * @param array $shift
- * @return bool|null
+ * @return int
  * @throws Exception
  */
 function Shift_update_by_psid($shift)
diff --git a/includes/model/UserAngelTypes_model.php b/includes/model/UserAngelTypes_model.php
index c744cdd7..b1005095 100644
--- a/includes/model/UserAngelTypes_model.php
+++ b/includes/model/UserAngelTypes_model.php
@@ -193,15 +193,17 @@ function UserAngelType_create($user, $angeltype)
  * Get an UserAngelType by its id.
  *
  * @param int $user_angeltype_id
- * @return array
+ * @return array|null
  */
 function UserAngelType($user_angeltype_id)
 {
-    return DB::selectOne('
+    $angelType = DB::selectOne('
       SELECT *
       FROM `UserAngelTypes`
       WHERE `id`=?
       LIMIT 1', [$user_angeltype_id]);
+
+    return empty($angelType) ? null : $angelType;
 }
 
 /**
@@ -209,11 +211,11 @@ function UserAngelType($user_angeltype_id)
  *
  * @param array $user
  * @param array $angeltype
- * @return array
+ * @return array|null
  */
 function UserAngelType_by_User_and_AngelType($user, $angeltype)
 {
-    return DB::selectOne('
+    $angelType = DB::selectOne('
           SELECT *
           FROM `UserAngelTypes`
           WHERE `user_id`=?
@@ -225,6 +227,8 @@ function UserAngelType_by_User_and_AngelType($user, $angeltype)
             $angeltype['id']
         ]
     );
+
+    return empty($angelType) ? null : $angelType;
 }
 
 /**
diff --git a/includes/model/UserDriverLicenses_model.php b/includes/model/UserDriverLicenses_model.php
index a1476f95..2c251d66 100644
--- a/includes/model/UserDriverLicenses_model.php
+++ b/includes/model/UserDriverLicenses_model.php
@@ -41,14 +41,16 @@ function UserDriverLicense_valid($user_driver_license)
  * Get a users driver license information
  *
  * @param int $user_id The users id
- * @return array
+ * @return array|null
  */
 function UserDriverLicense($user_id)
 {
-    return DB::selectOne('
+    $driverLicense = DB::selectOne('
         SELECT *
         FROM `UserDriverLicenses`
         WHERE `user_id`=?', [$user_id]);
+
+    return empty($driverLicense) ? null : $driverLicense;
 }
 
 /**
diff --git a/includes/model/UserWorkLog_model.php b/includes/model/UserWorkLog_model.php
index df0ec8f6..ff39ba8f 100644
--- a/includes/model/UserWorkLog_model.php
+++ b/includes/model/UserWorkLog_model.php
@@ -6,13 +6,15 @@ use Engelsystem\Database\Db;
  * Load a single work log entry.
  *
  * @param int $user_worklog_id
- * @return array
+ * @return array|null
  */
 function UserWorkLog($user_worklog_id)
 {
-    return Db::selectOne("SELECT * FROM `UserWorkLog` WHERE `id`=?", [
+    $workLog = Db::selectOne("SELECT * FROM `UserWorkLog` WHERE `id`=?", [
         $user_worklog_id
     ]);
+
+    return empty($workLog) ? null : $workLog;
 }
 
 /**
diff --git a/includes/model/User_model.php b/includes/model/User_model.php
index 70a03736..d2498462 100644
--- a/includes/model/User_model.php
+++ b/includes/model/User_model.php
@@ -406,44 +406,52 @@ function User_validate_planned_departure_date($planned_arrival_date, $planned_de
  * Returns user by id.
  *
  * @param int $user_id UID
- * @return array
+ * @return array|null
  */
 function User($user_id)
 {
-    return DB::selectOne('SELECT * FROM `User` WHERE `UID`=? LIMIT 1', [$user_id]);
+    $user = DB::selectOne('SELECT * FROM `User` WHERE `UID`=? LIMIT 1', [$user_id]);
+
+    return empty($user) ? null : $user;
 }
 
 /**
  * Returns User by api_key.
  *
  * @param string $api_key User api key
- * @return array Matching user, empty if not found
+ * @return array|null Matching user, null if not found
  */
 function User_by_api_key($api_key)
 {
-    return DB::selectOne('SELECT * FROM `User` WHERE `api_key`=? LIMIT 1', [$api_key]);
+    $user = DB::selectOne('SELECT * FROM `User` WHERE `api_key`=? LIMIT 1', [$api_key]);
+
+    return empty($user) ? null : $user;
 }
 
 /**
  * Returns User by email.
  *
  * @param string $email
- * @return array Matching user, empty on error
+ * @return array|null Matching user, null when not found
  */
 function User_by_email($email)
 {
-    return DB::selectOne('SELECT * FROM `User` WHERE `email`=? LIMIT 1', [$email]);
+    $user = DB::selectOne('SELECT * FROM `User` WHERE `email`=? LIMIT 1', [$email]);
+
+    return empty($user) ? null : $user;
 }
 
 /**
  * Returns User by password token.
  *
  * @param string $token
- * @return array Matching user, empty when not found
+ * @return array|null Matching user, null when not found
  */
 function User_by_password_recovery_token($token)
 {
-    return DB::selectOne('SELECT * FROM `User` WHERE `password_recovery_token`=? LIMIT 1', [$token]);
+    $user = DB::selectOne('SELECT * FROM `User` WHERE `password_recovery_token`=? LIMIT 1', [$token]);
+
+    return empty($user) ? null : $user;
 }
 
 /**