how could the value of current_user be inserted into error logs/emails when using Flask-Login?

Solution

mh = SMTPHandler(
    mailhost=app.config["MAIL_SERVER"],
    fromaddr=app.config["MAIL_DEFAULT_SENDER"],
    toaddrs=app.config["ERRORS_EMAIL"],
    subject="Error",
)
mh.setLevel(logging.ERROR)
mh.setFormatter(logging.Formatter('%(user)s - %(message)s'))
app.logger.addHandler(mh)
app.logger = LoggerAdapter(app.logger, {'user': current_user})

class CurrentUserFilter(logging.Filter):
    """
    Add a user attribute to all records
    """
    def filter(self, record):
        record.user = current_user
        return True  # Return True to pass the record to the next filter


mh = SMTPHandler(
    mailhost=app.config["MAIL_SERVER"],
    fromaddr=app.config["MAIL_DEFAULT_SENDER"],
    toaddrs=app.config["ERRORS_EMAIL"],
    subject="Error",
)
mh.setLevel(logging.ERROR)
mh.setFormatter(logging.Formatter('%(user)s - %(message)s'))
app.logger.addHandler(mh)
app.logger.addFilter(CurrentUserFilter())