Linq Except considering only one property

Question

I have two lists of object.

List<object1> obj1 = new List<object1>();

List<object2> obj2 = new List<object2>(); 

I want to do this:

obj2 = obj2.Except(obj1).ToList();

However, by reading other questions similar to mine, I understand that this doesn't work unless I override Equals.

I do not want to do that, but both obj2 and obj1 have a string property that is sufficient to see whether they are equal. If obj2.StringProperty is equivalent to obj1.StringProperty then the two can be considered equal.

Is there any way I can use Except, but by using only the string property to compare?

Answer 1

The Except method requires that the two collection types involved have the same element type. In this case the element types are different (object1 and object2) hence Except isn't really an option. A better method to use here is Where

obj2 = obj2
  .Where(x => !obj1.Any(y => y.StringProperty == x.StringProperty))
  .ToList();