Data not updating by scanning barcode

Question

I have a textfield in flutter and in that texfield I have a button where I have put the scan function where I scan barcode and pass result as argument to the exact screen where I have button for scanning.. the data gets saved screen doesn't update..

Padding(
                padding: const EdgeInsets.all(8.0),
                child: Container(
                  height: 70,
                  width: double.maxFinite,
                  color: Color.fromARGB(153, 142, 255, 146),
                  child: TextButton(
                    onPressed: () {
                    stockInController.scan();
                    },
                    child: Align(
                      alignment: Alignment.centerLeft,
                      child: Row(
                        children: [
                          Expanded(
                            child: Text(selectedProducts!.isEmpty 
                                ? 'Select Product'
                                : selectedProducts!.join(
                                    ', ')),  // Display selected product or placeholder
                          ),
                          IconButton(
                            onPressed: () => stockInController.scan(),
                            icon: Icon(Icons.barcode_reader),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              ),

 List<String?>? selectedProducts =
        Get.arguments != null && Get.arguments is List<String?>
            ? Get.arguments as List<String?>
            : [];

Future<void> scan() async {
  
  try {
    var result = await BarcodeScanner.scan();
    final scanResult = result.rawContent;
    DocumentSnapshot documentSnapshot =
        await dataCollection.doc(result.rawContent.toString()).get();
    
    if (documentSnapshot.exists) {
      String itemName = documentSnapshot['name'] as String;
      selectedItems.add(itemName);
          
      Get.to(const StockIn(), arguments: selectedItems);
    } else {
      Get.snackbar('Error', 'Product not available');
    }
  } catch (e) {
    Get.snackbar('Error', 'Failed to fetch data from Firestore: $e');
  }
}

Kindly help if anyone know about that issue.