Custom intersect in lambda

Question

I would like to know if this is possible to solve using a lambda expression:

List listOne = service.GetListOne();
List listTwo = service.Ge         


        

Answer 1

Sure you can! You can use this overload of Linq's Intersect extension method which takes an IEqualityComparer, like this:

public class FooComparer : IEqualityComparer 
{
    public bool Equals(Foo x, Foo y)
    {
        return x.Id == y.Id && x.someKey != y.someKey;
    }

    public int GetHashCode(Foo x)
    {
        return x.Id.GetHashCode();
    }
}

...

var comparer = new FooComparer();
List listOne = service.GetListOne();
List listTwo = service.GetListTwo();
List result = listOne.Intersect(listTwo, comparer).ToList();