Error while appending data to list with custom Model class(Dart)

I am new to dart and I am trying to create a basic inventory app with different types of chemicals.

I am trying to fetch data from firebase, which is getting back to me perfectly, but when I am trying to store it locally with a custom Model Class, its throwing me the following error

type ‘int’ is not a subtype of type ‘String’

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Here is the code for fetching and storing data locally

Future<void> getLoadedData() async {
final url = Uri.parse(
    'https://inventory-db0eb-default-rtdb.asia-southeast1.firebasedatabase.app/chemicalList.json?auth=$authToken');
try {
  final response = await http.get(url);
  final List<ChemModel> _tempChemical = [];

  final _tempChemList = json.decode(response.body) as Map<String, dynamic>;

  _tempChemList.forEach((elementId, value) {
    _tempChemical.add(
      ChemModel(
        id: ' ',
        name: ' ',
        // name: value['name'] ?? "Empty",
        formula: ' ',
        // formula: value['formula'] ?? "Empty",
        description: ' ',
        molWeight: double.parse(value['molWeight']),
        // description: value['description'] ?? "Empty",)
      ),
    );
  });

  _chemicalList = _tempChemical;
  notifyListeners();
} catch (error) {
  print(error);
  rethrow;
}}

This is my model class

class ChemModel with ChangeNotifier {
  String id;
  String name;
  String formula;
  double molWeight;
  String description;

  ChemModel(
      {required this.id,
      required this.name,
      required this.formula,
      this.description = "",
      this.molWeight = 0});
}

I’m not sure where I am going wrong.

>Solution :

model class may be a nuisance if you share a screenshot of the data source I can help more clearly

for exp :
I mean, the value from the data source is string, and if you’re trying to keep it as a int in the model class, you might get this kind of error.