C#•5mo ago

i dont know why i am still got `CS8602 - Dereference of a possibly null reference.` in that indexer

here is an indexer i still got this warning in the setter i dont know why

c#
        public string? this[int employee_id]
        {
            get => listEmployees?.FirstOrDefault(emp => emp.EmployeeId == employee_id)?.Name ?? "No Name Found";

            set => listEmployees.FirstOrDefault(emp => emp.EmployeeId == employee_id).Name = value;
        }

c#
        public string? this[int employee_id]
        {
            get => listEmployees?.FirstOrDefault(emp => emp.EmployeeId == employee_id)?.Name ?? "No Name Found";

            set => listEmployees.FirstOrDefault(emp => emp.EmployeeId == employee_id).Name = value;
        }

18 Replies

Angius•5mo ago

Well, listEmployees is nullable, apparently But you don't treat it as such in the setter You can't call FirstOrDefault() on a null null has no .Name property null cannot be set to a value

steven preadlyOP•5mo ago

then what are the clue for this how can i solve this nullable issue in that case

Angius•5mo ago

Does listEmployees need to be nullable, first of all? If it does... well, just check for null in the setter Use null-conditional operator like in the getter And so on

steven preadlyOP•5mo ago

no but when i remove the null ? public string this[int employee_id] i still have the same issue

Angius•5mo ago

Never have I mentioned removing it here Though, it seems this property can't actually return null So making it a string instead of string? is fine

steven preadlyOP•5mo ago

i did it like this set => listEmployees?.FirstOrDefault(emp => emp.EmployeeId == employee_id).Name = value; but now i have another issue The left-hand side of an assignment must be a variable, property or indexer

Angius•5mo ago

It can still be null Can't assign to null

steven preadlyOP•5mo ago

i will make a null check using the if condation insid the set

Angius•5mo ago

Yep

steven preadlyOP•5mo ago

even when i did it like so i still have the same wrnning

c#
            set
            {
                if(listEmployees != null) 
                {
                    listEmployees.FirstOrDefault(emp=> emp.EmployeeId == employee_id).Name = value;
                }
            }

c#
            set
            {
                if(listEmployees != null) 
                {
                    listEmployees.FirstOrDefault(emp=> emp.EmployeeId == employee_id).Name = value;
                }
            }

Angius•5mo ago

The result of FirstOrDefault() can be null

steven preadlyOP•5mo ago

ok i just want to remove the warnning

Angius•5mo ago

Check for null then

var emp = listEmployees?.FirstOrDefault(...);
if (emp != null)
{
    emp.Name = value;
}

var emp = listEmployees?.FirstOrDefault(...);
if (emp != null)
{
    emp.Name = value;
}

steven preadlyOP•5mo ago

aha it cant be checked on the same line i have to sperate the FirstOrDefault() then check for null

Angius•5mo ago

I mean, you can do

if (listEmployees?.FirstOrDefault(...) is {} emp)
{
    emp.Name = value;
}

if (listEmployees?.FirstOrDefault(...) is {} emp)
{
    emp.Name = value;
}

steven preadlyOP•5mo ago

but as we talked before i noticed that indexer is more complex than methods but i thhink it has its use cases thank you very mush i wan to make this as solved

Angius•5mo ago

$close

MODiX•5mo ago

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i dont know why i am still got `CS8602 - Dereference of a possibly null reference.` in that indexer