fix school year for all tables

app/Models/DiscountUsageModel.php

@@ -3,9 +3,12 @@
 namespace App\Models;
 
 use CodeIgniter\Model;
+use App\Models\Concerns\SchoolYearAutoFillTrait;
 
 class DiscountUsageModel extends Model
 {
+    use SchoolYearAutoFillTrait;
+
     protected $table = 'discount_usages';
     protected $primaryKey = 'id';
     
@@ -30,7 +33,8 @@ class DiscountUsageModel extends Model
         'voucher_id' => 'required|is_natural_no_zero',
         'invoice_id' => 'required|is_natural_no_zero',
         'user_id'    => 'permit_empty|is_natural_no_zero',
-        'used_at'    => 'valid_date'
+        'used_at'    => 'valid_date',
+        'school_year' => 'required|string|max_length[9]',
     ];
 
     protected $validationMessages = [