I'm developing a platform that collects users' data over time; some data are the user's first and last names.
In many cases, I won't be able to collect one or both of these fields immediately and when listing all users, or displaying the profile of a single user, I'd like to make it clear what are the missing fields in an elegant way.
For example, only having a first name could allow displaying "John" while only having the last name could result in "-- Doe". If none are available, maybe the best way would be to say "(no name available)" or "-- --".
How would you handle this, and have you seen any platform tackling this problem gracefully?