Intersect LINQ query

Question

If I have an IEnumerable where ClassA exposes an ID property of type long. Is it possible to use a Linq query to get all instances of ClassA with ID belonging to a second IE

Answer 1

You can do it, but in the current form, you'd want to use the Where extension method.

var results = original.Where(x => yourEnumerable.Contains(x.ID));

Intersect on the other hand will find elements that are in both IEnumerable's. If you are looking for just a list of ID's, you can do the following which takes advantage of Intersect

var ids = original.Select(x => x.ID).Intersect(yourEnumerable);