reconstruction of the project

app/Models/InvoiceStudentList.php

@@ -6,11 +6,11 @@ use App\Models\BaseModel;
 
 class InvoiceStudentList extends BaseModel
 {
-    // Specify the table name
-    protected $table = 'invoice_students_list'; // Primary key for the table
-    protected $primaryKey = 'id';
+    protected $table = 'invoice_students_list';
+
+    // ✅ CI: useTimestamps = true (created_at/updated_at)
+    public $timestamps = true;
 
-    // Specify which fields are allowed for mass assignment
     protected $fillable = [
         'invoice_id',
         'student_id',
@@ -24,15 +24,21 @@ class InvoiceStudentList extends BaseModel
         'semester',
     ];
 
-    // Enable auto-incrementing primary key
-    protected $useAutoIncrement = true;
+    protected $casts = [
+        'invoice_id' => 'integer',
+        'student_id' => 'integer',
+        'school_id'  => 'integer',
+        'enrolled'   => 'boolean',
+    ];
 
-    // Specify return type as an array
+    /* Optional relationships */
+    public function invoice()
+    {
+        return $this->belongsTo(Invoice::class, 'invoice_id');
+    }
 
-    // Automatically set `created_at` and `updated_at` fields
-    public $timestamps = true;
-
-    // Specify the names of the timestamp fields
-    const CREATED_AT = 'created_at';
-    const UPDATED_AT = 'updated_at';
-}
+    public function student()
+    {
+        return $this->belongsTo(Student::class, 'student_id');
+    }
+}