[FEAT] Update StockTransferDelivery and TransferDeliveryDTO to allow optional SupplierId

internal/modules/inventory/transfers/services/transfer.service.go

@@ -196,6 +196,11 @@ func (s *transferService) CreateOne(c *fiber.Ctx, req *validation.TransferReques
 	}
 
 	for _, delivery := range req.Deliveries {
+		// Skip supplier validation if SupplierID is 0 (optional)
+		if delivery.SupplierID == 0 {
+			continue
+		}
+
 		supplier, err := s.SupplierRepo.GetByID(c.Context(), uint(delivery.SupplierID), nil)
 		if err != nil {
 			if errors.Is(err, gorm.ErrRecordNotFound) {
@@ -310,9 +315,16 @@ func (s *transferService) CreateOne(c *fiber.Ctx, req *validation.TransferReques
 
 		var deliveries []*entity.StockTransferDelivery
 		for _, delivery := range req.Deliveries {
+			supplierId := func() *uint64 {
+				if delivery.SupplierID > 0 {
+					id := uint64(delivery.SupplierID)
+					return &id
+				}
+				return nil
+			}()
 			deliveries = append(deliveries, &entity.StockTransferDelivery{
 				StockTransferId:   entityTransfer.Id,
-				SupplierId:        uint64(delivery.SupplierID),
+				SupplierId:        supplierId,
 				VehiclePlate:      delivery.VehiclePlate,
 				DriverName:        delivery.DriverName,
 				ShippingCostItem:  delivery.DeliveryCostPerItem,
@@ -458,6 +470,11 @@ func (s *transferService) CreateOne(c *fiber.Ctx, req *validation.TransferReques
 
 		if len(req.Deliveries) > 0 {
 			for _, delivery := range req.Deliveries {
+				// Skip adding to expensePayloads if SupplierID is 0 (optional)
+				if delivery.SupplierID == 0 {
+					continue
+				}
+
 				for _, prod := range delivery.Products {
 					detail := detailMap[uint64(prod.ProductID)]
 					if detail == nil {