Question

I have two IEnumerable lists.

I want to populate values into the second list based upon the results in the first.

The first IEnumerable list is populated like this:

IEnumerable<SelectListItem> selectedList =
CategoryServices.GetAttributesByCategoryID(categoryID); // it returns selected attributes for a particular category

I have a function to get all attributes. Now I want to get another list which contains all other attributes (ie, the items not present in selectedList). I tried this:

IEnumerable<SelectListItem> available =
CategoryServices.GetAllAttributes().Where(a => !selectedList.Contains(a));

But its not filtering. I am getting all attributes… Any ideas?

Answer 1

Make sure your SelectListItem class implements IEquatable<SelectListItem> so the Contains() method has a proper means for determining equality of instances.