def by_user_name(cls, username):
"""A class method that permits to search users
based on their user_name attribute.
"""
return DBSession.query(cls).filter(cls.user_name==username).first()
def by_email_address(cls, email):
"""A class method that can be used to search users
based on their email addresses since it is unique.
"""
return DBSession.query(cls).filter(cls.email_address==email).first()