flutter/dart errors encountered passing a List<String> with onGenerate route to another screen

Question

I'm new to flutter and I'm trying to pass a List to another screen using onGenerate routes

I'm getting an error

The argument type 'Object?' can't be assigned to the parameter type 'List<String>'.

I also tried the answer here How to pass value through constructor to another screen using generating route method with flutter?

So I changed my affected route code into:

case eightyTenAddLot:
      final value = settings.arguments as List<String>;
      return MaterialPageRoute(builder: (context) => EightyTenAddLot(
          addLotData: value)
      );

Unfortunately I'm getting a new error

The following _CastError was thrown while handling a gesture:
type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'List<String>' in type cast

I ran out of ideas. Maybe someone can give a hand or helpful ideas are very much appreciated.

Here are my codes:

route.dart

// Route Names
const String loginPage = 'loginPage';

const String dashBoard = 'dashboard';
const String eightyTenTabletPg2 = 'eightyTenTabletPg2';
const String eightyTenAddLot = 'eightyTenAddLot';


// Control our page route flow
Route<dynamic> generateRoute(RouteSettings settings) {

  switch (settings.name) {
    case loginPage:
      return MaterialPageRoute(builder: (context) => LoginPage());
    case dashBoard:
      return MaterialPageRoute(builder: (context) => Dashboard());
    case eightyTenTabletPg2:
      return MaterialPageRoute(builder: (context) => EightyTenTabletPg2(
          recvNo: settings.arguments.toString()
      ));
    case eightyTenAddLot:
      print('settings.arguments: ${settings.arguments}');
      return MaterialPageRoute(builder: (context) => EightyTenAddLot(addLotData: settings.arguments,));

    default:
      throw('The route does not exist yet.');
  }
}

eighty_ten_add_lot.dart

class EightyTenAddLot extends StatefulWidget {

  final List<String> addLotData;

  const EightyTenAddLot({Key? key, required this.addLotData}) : super(key: key);

  @override
  _EightyTenAddLotState createState() => _EightyTenAddLotState();
}

class _EightyTenAddLotState extends State<EightyTenAddLot> {
 
 @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
          automaticallyImplyLeading: true,
          title: const Text('8010 - Add Lot'),
          leading: IconButton(icon: const Icon(Icons.arrow_back),
            onPressed:() => Navigator.pop(context, false),
          )
      ),
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            child: Column(
              // mainAxisSize: MainAxisSize.max,
              mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  SizedBox(
                    width: 300,
                    child: Container(
                      decoration: const BoxDecoration(
                        color: Color(0xFF3F51B5),
                        borderRadius: BorderRadius.all(Radius.circular(5)),
                      ),
                      child: const Padding(
                        padding: EdgeInsets.all(8.0),
                        child: Center(
                          child: Text("Add Lot",
                            style: TextStyle(
                              fontSize: 22.0,
                              color: Colors.white,
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                  const SizedBox(
                    height: 20.0,
                  ),
                  //main content
                  Container(
                    padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 20),
                    width: MediaQuery.of(context).size.width * 0.5,
                    decoration: BoxDecoration(
                        color: Colors.white,
                        borderRadius: BorderRadius.all(Radius.circular(15)),
                        boxShadow: [
                          BoxShadow(
                              blurRadius: 10, color: Colors.grey.shade300, spreadRadius: 5)
                        ]),
                    child: Column(
                        children: [
                          const SizedBox(
                            height: 2.0,
                          ),
                          _createLabelInput('Managed Date'),
                          const SizedBox(
                            height: 2.0,
                          ),
                          _createLabelInput('Expiration Date'),
                          const SizedBox(
                            height: 2.0,
                          ),
                          _createLabelInput('LOT'),
                          const SizedBox(
                            height: 2.0,
                          ),
                          _createLabelInput('Inspected Qty.'),
                          // Submit button
                          SizedBox(
                            height: 50,
                            child: ElevatedButton(
                              child: const Text(
                                'Submit',
                                style: TextStyle(
                                  fontSize: 22.0,
                                  fontWeight: FontWeight.bold,
                                ),
                              ),
                              onPressed: () {
                                print('addLotMap: $addLotMap');
                                //_eightyTen_40W(mngDateController.text, expiryDateController.text, lotController.text, inspectedQtyController.text);
                              },
                            ),
                          ),
                          const SizedBox(
                            height: 10.0,
                          )
                        ]
                    ),
                  ),
                ]
            ),
          ),
        ),
      ),
    );
  }
}

Answer 1

It seems to me you passing Map instead of List. Check object you passing to the Navigator.pushNamed. It usually happens when you pass a snapshot as an argument you may not know what type you passing.