C# LINQ Intersect 2 Different Type Lists and Return one Type

Question

I am trying to find common rows in 2 lists as follows:

public class ListA
{
        public string Id { get; set; }
        public string Name { get; set; }
}

List<ListA> listA = new List<ListA>();
List<string> listB = new List<string>();

List<ListA> intersect = listA.Where(x => listB.Any(y => y == x.Id)).ToList();

So the above Linq query will get me all common items in the 2 lists based on Id property, How can I do the same using Intersect/IntersectBy Id and return the type of ListA?

Answer 1

Use the IntersectBy LINQ method. This will let you compare the Id property from each ListA entry against another list of the same type as the extracted property.

IEnumerable<ListA> intersect = listA.IntersectBy(listB, a => a.Id);