Question

Background: I have an ASP.NET MVC view page with a MultiSelectList in the View Model. I want to populate a label with the list of SelectedValues from that MultiSelectList object. The list is stored within the MultiSelectList with a type of IDName:

public class IDName {
    public int ID {get; set;}
    public string Name {get; set;}
}

So MultiSelectList.Items is an IEnumerable containing a list of IDName’s. I can do a foreach over this list and grab .Name to get the name of each entry. But, I only want to do this if the ID is in MultiSelectList.SelectedItems, which appears to be a string[] and looks like:

["1", "3", "4"]

So, I want to just get the IDName.Name when IDName.ID is in the SelectedItems list.

I’m pretty new to both MVC and C# so I’m not sure the best way to do that. Any suggestions?

Update #2:

OK, I was being dense. This works:

list.Items
  .Cast<IDName>()
  .Where(x => list.SelectedValues.Cast<string>().Contains(x.ID.ToString()))

SelectedValues is actually an IEnumerable containing a string[].

Answer 1

Try the following.

var selected = MultiSelectList.Items
  .Cast<IDName>()
  .Where(x => MultiSelectList.SelectedItems.Contains(x.Name));

What this does is process all of the items in the MultiSelectList.Items collection. It will then cast all of them to a strongly typed IDName instance. The where clause will filter the collection to only the items where the Name field matches an entry in the SelectedItems array.