Separate username/email from userDoc _id

[peteruithoven]

As far as I understand it superlogin uses usernames as _id's in the userDB.

• It looks like the username is validated using a regexp (/^[a-z0-9_-]{3,16}$/), this means we limit the userid's based on what couchdb can handle as _id's?
• Doesn't this make it harder / impossible to change usernames later on? (While there are methods to change the E-mail and password there is no change username method)

When enabling the emailUsername the E-mail is used as _id. Which solves the uncommon characters issue, but doesn't make changing it easier.

It looks like Hoodie for example separated the username from the id. https://github.com/hoodiehq/hoodie-account-client#accountid

Wouldn't it be safer / more extensible to separate the _id from the username/email?