/**
* Create billets.
*
* @param Illuminate\Database\Eloquent\Collection $students
* @param string $refer YYYYMM
*
* @return void
*/
public function createBillets($students, $refer)
{
$students->each(function ($student) use($refer) {
$exists = $student->whereHas('billets', function ($q) use($refer, $student) {
$q->where('refer', $refer)->where('student_id', $student->id)->select('id');
})->exists();
if (!$exists) {
$this->createBillet($student, $refer);
}
});
}
