We have a requirement to have a user profile with multiple aliases along with username to login. That means user can use alias (can be stored in user metadata) to login. So use can use username/email/alias to login.
How can we implement this & how can we ensure that the alias is unique across the database & username field? I saw this custom database option, but do we need to host our own database, and will there be an option to control this login verification?
Alias is not supported by Auth0 for login purposes. You can use a username or email to login.
If you would like to use an alias a custom UI + Custom DB would be required. This implementation has many limitations and it defeats the purpose of using Auth0. The use of Custom DB scripts is used as a temporary solution until users are migrated across to Auth0. I would highly recommend reconsidering the use of aliases.