"Nullable object must have a value" when Mapping bool? to bool? - asp.net-core

Question

In my app, I fetch two attributes IsLoopCar and LoopStatusSet from a DB and Store them to a model class:
private static ChecklistModel MapChecklistModel(DataRow row)
{
var checklist = new ChecklistModel
{
IsLoopCar = Convert.IsDBNull(row["IsLoopCar"]) ? null : Convert.ToBoolean(row["IsLoopCar"]),
LoopStatusSet = Convert.IsDBNull(row["LoopStatusSet"]) ? null : Convert.ToBoolean(row["LoopStatusSet"])
}
}
In my model class and the viewModel I map my model class to, the data type of these two attributes is bool?
public class ChecklistModel
{
public bool? IsLoopCar { get; set; }
public bool? LoopStatusSet { get; set; }
}
public class GetPaymentInformationViewModel
{
public bool? IsLoopCar { get; set; }
public bool? LoopStatusSet { get; set; }
}
The value of the attribute in my DB is null. When I map the model to the viewmodel using AutoMapper (7.0.1), I get an error message which I don't understand:
GetPaymentInformationViewModel gpivm = _mapper.Map<ChecklistModel, GetPaymentInformationViewModel>(checklist);
The mapping configuration is very basic:
CreateMap<ChecklistModel, GetPaymentInformationViewModel>();
The error message is:
InvalidOperationException: Nullable object must have a value.
I don't understand what's the point in mapping nullable bools, when they have to have a value. I need to have this value to be null when i pass it to the view because it works as kind of a checkpoint where the user must select a yes/no value with no initial default value set.

Answer 1

Based on the recommendation of Lucian, I tried to reproduce the problem with a fresh console app but it didn't fail there. As it turned out, the problem was in my view model where I had written a custom setter that makes no sense:
[Required]
[Display(Name = "IsLoopCar")]
public bool? IsLoopCar
{
get
{
return _IsLoopCar;
}
set
{
if (value.Value == true)
_IsLoopCar = value.Value;
else
{
_IsLoopCar = value.Value;
LoopStatusSet = null;
}
}
}
The field value.Value cannot be read because it does not exists. It's supposed to be like that:
[Required]
[Display(Name = "IsLoopCar")]
public bool? IsLoopCar
{
get
{
return _IsLoopCar;
}
set
{
if (value == true)
_IsLoopCar = value;
else
{
_IsLoopCar = value;
LoopStatusSet = null;
}
}
}