diff --git a/app/Models/Exam.php b/app/Models/Exam.php
index b2cd12ca..07fb30d4 100644
--- a/app/Models/Exam.php
+++ b/app/Models/Exam.php
@@ -3,6 +3,8 @@
 namespace App\Models;
 
 use Carbon\Carbon;
+use Google\Service\Dataproc\RegexValidation;
+use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Model;
 
 class Exam extends NexusModel
@@ -162,4 +164,28 @@ class Exam extends NexusModel
         return implode("<br/>", $arr);
     }
 
+    public function begin(): Attribute
+    {
+        return new Attribute(
+            get: fn ($value) => $value ? Carbon::parse($value) : Carbon::now()
+        );
+    }
+
+    public function end(): Attribute
+    {
+        return new Attribute(
+            get: function ($value, $attributes) {
+                if ($value) {
+                    return Carbon::parse($value);
+                }
+                if (!empty($attributes['duration'])) {
+                    /** @var Carbon $begin */
+                    $begin = $this->begin;
+                    return $begin->addDays($attributes['duration']);
+                }
+                throw new \RuntimeException("No specific end or duration");
+            }
+        );
+    }
+
 }
diff --git a/app/Models/ExamUser.php b/app/Models/ExamUser.php
index 8ed336d5..fb129e26 100644
--- a/app/Models/ExamUser.php
+++ b/app/Models/ExamUser.php
@@ -67,16 +67,14 @@ class ExamUser extends NexusModel
     public function getBeginAttribute()
     {
         $begin = $this->getRawOriginal('begin');
-        $end = $this->getRawOriginal('end');
-        if ($begin && $end) {
+        if ($begin) {
             do_log(sprintf('examUser: %s, begin from self: %s', $this->id, $begin));
             return $begin;
         }
 
         $exam = $this->exam;
         $begin = $exam->getRawOriginal('begin');
-        $end = $exam->getRawOriginal('end');
-        if ($begin && $end) {
+        if ($begin) {
             do_log(sprintf('examUser: %s, begin from exam(%s): %s', $this->id, $exam->id, $begin));
             return $begin;
         }
@@ -90,17 +88,15 @@ class ExamUser extends NexusModel
 
     public function getEndAttribute()
     {
-        $begin = $this->getRawOriginal('begin');
         $end = $this->getRawOriginal('end');
-        if ($begin && $end) {
+        if ($end) {
             do_log(sprintf('examUser: %s, end from self: %s', $this->id, $end));
             return $end;
         }
 
         $exam = $this->exam;
-        $begin = $exam->getRawOriginal('begin');
         $end = $exam->getRawOriginal('end');
-        if ($begin && $end) {
+        if ($end) {
             do_log(sprintf('examUser: %s, end from exam(%s): %s', $this->id, $exam->id, $end));
             return $end;
         }
diff --git a/app/Repositories/ExamRepository.php b/app/Repositories/ExamRepository.php
index 08dd1eec..de2b5bdb 100644
--- a/app/Repositories/ExamRepository.php
+++ b/app/Repositories/ExamRepository.php
@@ -1018,6 +1018,8 @@ class ExamRepository extends BaseRepository
         $size = 1000;
         $minId = 0;
         $result = 0;
+        $begin = $exam->begin;
+        $end = $exam->end;
         while (true) {
             $logPrefix = sprintf('[%s], exam: %s, size: %s', __FUNCTION__, $exam->id , $size);
             $users = (clone $baseQuery)->where("$userTable.id", ">", $minId)->limit($size)->get();
@@ -1033,6 +1035,8 @@ class ExamRepository extends BaseRepository
                 $insert = [
                     'uid' => $user->id,
                     'exam_id' => $exam->id,
+                    'begin' => $begin,
+                    'end' => $end,
                     'created_at' => $now,
                     'updated_at' => $now,
                 ];
diff --git a/include/constants.php b/include/constants.php
index 3be2e708..be847c06 100644
--- a/include/constants.php
+++ b/include/constants.php
@@ -1,6 +1,6 @@
 <?php
 defined('VERSION_NUMBER') || define('VERSION_NUMBER', '1.8.12');
-defined('RELEASE_DATE') || define('RELEASE_DATE', '2024-04-09');
+defined('RELEASE_DATE') || define('RELEASE_DATE', '2024-04-10');
 defined('IN_TRACKER') || define('IN_TRACKER', false);
 defined('PROJECTNAME') || define("PROJECTNAME","NexusPHP");
 defined('NEXUSPHPURL') || define("NEXUSPHPURL","https://nexusphp.org");