how to handle null safety during api call flutter?

Question

am trying to do an API call where am getting an error to hangle null safety variable must be assigned.

here is my code

Future<LoginResponseModel> loginCustomer(
      String username, String password) async {
    LoginResponseModel model;

    try {
      var response = await Dio().post(Config.tokenURL,
          data: {
            "username": username,
            "password": password,
          },
          options: Options(headers: {
            HttpHeaders.contentTypeHeader: "application/x-www-form-urlencoded",
          }));

      if (response.statusCode == 200) {
        model = LoginResponseModel.fromJson(response.data);
      }
    } on DioError catch (e) {
      print(e.message);
    }
    return model;
  }

exception am getting

The non-nullable local variable 'model' must be assigned before it can be used. Try giving it an initializer expression, or ensure that it's assigned on every execution path.dart (not_assigned_potentially_non_nullable_local_variable)

is there any solution to handle this

tried "?" it's not working.

Screenshot

Answer 1

  Future<LoginResponseModel?> loginCustomer(
      String username, String password) async {
    LoginResponseModel? model;

    try {
      var response = await Dio().post(Config.tokenURL,
          data: {
            "username": username,
            "password": password,
          },
          options: Options(headers: {
            HttpHeaders.contentTypeHeader: "application/x-www-form-urlencoded",
          }));

      if (response.statusCode == 200) {
        model = LoginResponseModel.fromJson(response.data);
      }
    } on DioError catch (e) {
      print(e.message);
    }
    return model;
  }