diff --git a/app/Booking.php b/app/Booking.php
index bcfaf56c..0ff1679f 100644
--- a/app/Booking.php
+++ b/app/Booking.php
@@ -100,15 +100,17 @@ class Booking extends Model
         return $this->hasOne(Invoice::class);
     }
 
-    public function delete()
-    {
-        $this->supplierBooking()->delete();
-        $this->chinaBankSlip()->delete();
-        $this->userBankSlip()->delete();
-        $this->purchaseOrder()->delete();
-        $this->invoice()->delete();
-
-        return parent::delete();
+    public static function boot() {
+        parent::boot();
+        self::deleting(function($booking) {
+            $booking->userBankSlip()->delete();
+            $booking->supplierBooking()->delete();
+            $booking->chinaBankSlip()->each(function($bankslip) {
+                $bankslip->delete();
+            });
+            $booking->purchaseOrder()->delete();
+            $booking->invoice()->delete();
+        });
     }
 
 
diff --git a/app/Invoice.php b/app/Invoice.php
index 1e07a23f..2608bf2e 100644
--- a/app/Invoice.php
+++ b/app/Invoice.php
@@ -20,11 +20,15 @@ class Invoice extends Model
         return $this->hasMany(InvoiceStatuses::class);
     }
 
-    public function delete()
-    {
-        $this->invoiceDetails()->delete();
-        $this->invoiceStatuses()->delete();
-
-        return parent::delete();
+    public static function boot() {
+        parent::boot();
+        self::deleting(function($invoice) {
+            $invoice->invoiceDetails()->each(function($invoiceDetails) {
+                $invoiceDetails->delete();
+            });
+            $invoice->invoiceStatuses()->each(function($invoiceStatuses) {
+                $invoiceStatuses->delete();
+            });
+        });
     }
 }