Nizar's .NET Blog

LINQ : Implementing IN and NOT IN

February 12th, 2009 Nizar 6 comments

I got tried of typing

  var result = from s in source
                  where items.Contains(s)
                  select s;

and so I implemented the IN and NOT IN methods as extension methods:

public static IQueryable<T> In<T>(this IQueryable<T> source, 
                            IQueryable<T> checkAgainst)
{
   return from s in source 
            where checkAgainst.Contains(s) 
            select s;
}
 
public static IQueryable<T> NotIn<T>(this IQueryable<T> source, 
                                  IQueryable<T> checkAgainst)
{
   return from s in source 
            where !checkAgainst.Contains(s) 
            select s;
}