@rafaelcosta this might be a client pattern for users:
* selection of common profiles, with username field. Url set by client.
* Other, with url and username fields.
Maybe no need for separate ID field, since each only needs one?
@rafaelcosta@ludolphus still, in my thinking, clients aren't offering users to enter URLs for the known profiles anyway: they'd say "What's your twitter handle?" and then create the url itself using that.