Question

First example which works:

public class Test
{
    public int ID;
    public string Name;
}

List<int> list1 = Load1();
List<Test> list2 = Load2();

var query = list2.Where(c => list1.Contains(c.ID));

Now I would like to use two lists of objects as a source and get list of objects that have this same values for member ID.

List<Test> list1 = Load2();
List<Test> list2 = Load2();

Below doesn’t compile:

var query = list2.Where(c => **list1.ID.Contains**(c.ID));

I know it is wrong but placed it here for better understanding.
I would appreciate someone to show me the right path 🙂

Regards
Mariusz

Answer 1

You could make your Test class equatable:

public class Test : IEquatable<Test>
{
  public int Id {get;set;}
  public bool Equals(Test other)
  {
    return this.Id == other.Id;
  }
}

Then this would work:

list1.Where(item => list2.Contains(item));