public function qualityAssuranceModules($courseId, $currenModuleIdsArr)
{
$modules = Module::where('course_id', '=', $courseId)->select('module_id')->get();
$fromDBArr = array();
foreach ($modules as $mod) {
$fromDBArr[] = $mod['module_id'];
}
$toBeDeleted = array_diff($fromDBArr, $currenModuleIdsArr);
foreach ($toBeDeleted as $module) {
//TODO: verify cascading delete
Module::where('course_id', '=', $courseId)->where('module_id', '=', intval($module))->delete();
}
}
