how to resolve - type 'Null' is not a subtype of type 'String' in type cast?

im trying to fetch data from my sql db , everytime i fetch the data and try to display it on ,my app i keep on getting the error

> I/flutter ( 6564): type 'Null' is not a subtype of type 'String' in
> type cast

the code below is the logic that pulls the data from the db , ive checked for sources on the internet where it shows I had to use json.decode , i did this then printed the values on the consoles and it displays the values from db , however when i try to map the values it shows nothing - hence the error -

final getDataProvider = FutureProvider<List<DataModel>>((ref) async {
  return ref.watch(dataControllerProvider).getData();
});

final dataControllerProvider = Provider((ref) => DataController());

class DataController {

  Future<List<DataModel>> getData() async {
    try {
      final res = await http.get(Uri.parse(API.getDataMenu));
      List dataFromDB = jsonDecode(res.body);

      print(dataFromDB);

      return dataFromDB.map((e) => DataModel.fromJson(e)).toList();
    } catch (e) {
      print(e.toString());
      return []; // Return an empty list or handle the error case appropriately
    }
  }
}

code below is where i want to display the data -

 Widget build(BuildContext context, WidgetRef ref) {
    final dataAsync = ref.watch(getDataProvider);
    return Scaffold(
        body: dataAsync.when(
            data: (data) {
              List<DataModel> dataList = data.map((e) => e).toList();
              return ListView.builder(
                  itemCount: dataList.length,
                  itemBuilder: (BuildContext context, int index) {
                    return Column(
                      children: [
                        Text(dataList[index].Name)
                      ],
                    );
                  });
            },
            error: (error, stackTrace) => ErrorText(error: error.toString()),
            loading: () => const Loader()));
  }
}

In your DataModel make sure that the String values is nullable like that

String? parameter;

Another solution is to make a check inside fromJson function like that

 ChatDetailsModel.fromJson(dynamic json) {
    parameter = json['parameter'] ?? "";
 }

This error comes up when you're trying to assign a different type of value to an already typed variable. In your case, you're trying to assign a Null value to a variable that is a non-nullable type of String.

Essentially, this line is what's causing the error:

return dataFromDB.map((e) => DataModel.fromJson(e)).toList();

What I would suggest you to do is to look inside your DataModel and search for a String type of variable and make it nullable.
For eg. Let's consider the name variable.
Right now it must be like this:

String name;

Make it like this:

String? name;

And finally in your UI, add a nullable expression like this:

return Column(
  children: [
    Text(dataList[index].Name!.toString())
  ],
);

The toString() is added because you will receive a null safety error otherwise. Maybe add an if statement before displaying, to check if the value is non-null.