void

lib/infrastructure/order/dtos/order_dto.dart

@@ -136,4 +136,23 @@ class OrderItemDto with _$OrderItemDto {
     printerType: printerType ?? '',
     paidQuantity: paidQuantity ?? 0,
   );
+
+  factory OrderItemDto.fromDomain(OrderItem orderItem) => OrderItemDto(
+    id: orderItem.id,
+    orderId: orderItem.orderId,
+    productId: orderItem.productId,
+    productName: orderItem.productName,
+    productVariantId: orderItem.productVariantId,
+    productVariantName: orderItem.productVariantName,
+    quantity: orderItem.quantity,
+    unitPrice: orderItem.unitPrice,
+    totalPrice: orderItem.totalPrice,
+    modifiers: orderItem.modifiers,
+    notes: orderItem.notes,
+    status: orderItem.status,
+    createdAt: orderItem.createdAt.toIso8601String(),
+    updatedAt: orderItem.updatedAt.toIso8601String(),
+    printerType: orderItem.printerType,
+    paidQuantity: orderItem.paidQuantity,
+  );
 }

lib/infrastructure/order/dtos/order_request_dto.dart

@@ -98,11 +98,18 @@ class OrderItemRequestDto with _$OrderItemRequestDto {
         notes: request.notes,
       );
 
-  Map<String, dynamic> toRequest() => {
-    "product_id": productId,
-    "product_variant_id": productVariantId,
-    "quantity": quantity,
-    "unit_price": unitPrice,
-    "notes": notes,
-  };
+  Map<String, dynamic> toRequest() {
+    Map<String, dynamic> data = {
+      "product_id": productId,
+      "quantity": quantity,
+      "unit_price": unitPrice,
+      "notes": notes,
+    };
+
+    if (productVariantId != null && productVariantId != '') {
+      data["product_variant_id"] = productVariantId;
+    }
+
+    return data;
+  }
 }