LINQ中的Coalesce/IsNull功能

Question

如果某个属性的某个条件例如/ empty,我怎样才能使类中的属性返回某个字符串

public class Person
{
  public string Name{get;set;}
  publc string MiddleName{get;set;}
  public string Surname{get;set;}
  public string Gender{get;set;}
}

List<Person> people = repo.GetPeople();
List<Person> formatted = people.GroupBy(x=>x.Gender).//?? format Gender to be a certain string eg/"Not Defined" if blank 

Answer 1

people.GroupBy(x=>x.Gender ?? "Not Available").ToList();

更新:(捕捉空字符串)

people.GroupBy(x=> String.IsNullOrWhiteSpace(x.Gender) ? "None" : x.Gender).ToList();