Question

Got a List of “ClientContacts” — which have EITHER a LastName (in the case of a human) OR an EntityName (in the case of a general-use contact, such as [e-mail]).

What I want to do is SORT this List alphabetically by LastName, and in the case where no LastName exists (in other words, an EntityName exists), to treat that EntityName as a LastName, and continue the Sort as if it were a LastName.

So that the desired result looks like:

1. Bond James
2. Customer Support
3. Gates Bill
4. Tech Support
5. Williams Robin

---

This causes a crash, because it runs into some ClientContacts that don’t have a LastName.

clientContactList.Sort(
    delegate(ClientContact c1, ClientContact c2) 
        { return c1.LastName.CompareTo(c2.LastName); });

And the following allows me to get through without crashing, and it sorts it by ClientContact EntityName’s first, and THEN LastNames:

            list.Sort(delegate(ClientContact c1, ClientContact c2) {
            try
            {
                return c1.LastName.CompareTo(c2.LastName);
            }
            catch
            {
                try
                {
                    return c1.EntityName.CompareTo(c2.LastName);
                }
                catch
                {
                    return c1.EntityName.CompareTo(c2.EntityName);
                }

            }
        });

resulting in:

1. Customer Support
2. Tech Support
3. Bond James
4. Gates Bill
5. Williams Robin

---

How can I get my list sorted to look like the above desired result?

Answer 1

Try using this comparison instead:

(c1.LastName ?? c1.EntityName).CompareTo(c2.LastName ?? c2.EntityName)