How can I make my string property nullable?

Solution 1:

String is a reference type and always nullable, you don't need to do anything special. Specifying that a type is nullable is necessary only for value types.

Solution 2:

C# 8.0 is published now so you can make reference types nullable too. For this you have to add

#nullable enable

Feature over your namespace. It is detailed here

For example something like this will work:

#nullable enable
namespace TestCSharpEight
{
  public class Developer
  {
    public string FullName { get; set; }
    public string UserName { get; set; }

    public Developer(string fullName)
    {
        FullName = fullName;
        UserName = null;
    }
}}

Also you can have a look this nice article from John Skeet that explains details.

Solution 3:

System.String is a reference type so you don't need to do anything like

Nullable<string>

It already has a null value (the null reference):

string x = null; // No problems here

Solution 4:

Strings are nullable in C# anyway because they are reference types. You can just use public string CMName { get; set; } and you'll be able to set it to null.

Solution 5:

It's been a while when the question has been asked and C# changed not much but became a bit better. Take a look Nullable reference types (C# reference)

string notNull = "Hello";
string? nullable = default;
notNull = nullable!; // null forgiveness

C# as a language a "bit" outdated from modern languages and became misleading.

for instance in typescript, swift there's a "?" to clearly say it's a nullable type, be careful. It's pretty clear and it's awesome. C# doesn't/didn't have this ability, as a result, a simple contract IPerson very misleading. As per C# FirstName and LastName could be null but is it true? is per business logic FirstName/LastName really could be null? the answer is we don't know because C# doesn't have the ability to say it directly.

interface IPerson
{
  public string FirstName;
  public string LastName;
}