C# Recieving NullReference error when using Where Contains

Question

When filtering a list using lambda where and contains, I get a NullReference error

var servers = _context.Servers.ToList();
servers = servers.Where(t => t.Technology.Contains(technology)).ToList();

But I get a this error:

Exception thrown: 'System.NullReferenceException' in ServerBuildApp.dll ServerBuildApp.Models.Servers.Technology.get returned null.

The list of servers contains a 'Technology' property and it contains the string I am passing it, for example "BIZ"

Any ideas? Or am I doing this completely wrong?

Answer 1

You need to check the t.Technology for null.

var servers = _context.Servers.ToList();
servers = servers.Where(t => t.Technology?.Contains(technology) is true).ToList();

You should check t.Technology for null and then check it contains.