Background

Understanding reference types and their nullable nature in C# programming is foundational. Reference types in C# have always been nullable, meaning that variables of any reference type can be assigned a value of null. In previous versions of C#, dereferencing a null variable was permitted without any checks.

In this article, we delve into the core aspects of handling nullable reference types in .NET, a crucial skill for modern C# programming.

The Nullable Reference Types feature was introduced in C# 8 to address this issue, and with the release of .NET 6, this feature is now enabled by default.

Example

Let's say we have a class:

In .Net we will get a warning for underlined properties:

CS8618: Non-nullable field 'Name' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

How to handle?

Method #1

Steps

• Open .csproj project file

• Inside the PropertyGroup change Nullable to disable

Result: We won't get any more warnings for null references, but we can potentially run into a Null Reference Exception if we don't check objects for null before using them.

Method #2

Steps

• Make properties nullable reference type by using "?" .

Method #3

Steps

• Assign a default value to properties.

Method #4

Steps

• Write a compiler directive #nullable to disable (or enable) feature.

If you have a .NET 6 project, open it now and try it.

If you haven't, make a coffee and check out these examples directly on my GitHub repository