flask-security login via username and not email

To login with a username instead of an email address (using Flask-Security 1.7.0 or higher), you can replace the email field with a username field in the User model

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(255), unique=True, index=True)
    password = db.Column(db.String(255))
    active = db.Column(db.Boolean())
    confirmed_at = db.Column(db.DateTime())
    roles = db.relationship('Role', secondary=roles_users,
                            backref=db.backref('users', lazy='dynamic'))

and update the app configuration.

app.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = 'username'

Next, to allow users to login using a username instead of an email, we will use the fact that the LoginForm validation method assumes the user identity attribute is in the email form field.

from flask_security.forms import LoginForm
from wtforms import StringField
from wtforms.validators import InputRequired

class ExtendedLoginForm(LoginForm):
    email = StringField('Username', [InputRequired()])

# Setup Flask-Security
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore,
                    login_form=ExtendedLoginForm)

This way, we can login using a username without rewriting the validation method or the login template. Of course, this is a hack and the more correct approach would be to add a custom validate method, which checks a username form field, to the ExtendedLoginForm class and to update the login template accordingly.

However, the approach above makes it easy to login with a username or an email address. To do this, define a user model with both a username and email field.

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)
    username = db.Column(db.String(255), unique=True, index=True)
    password = db.Column(db.String(255))
    active = db.Column(db.Boolean())
    confirmed_at = db.Column(db.DateTime())
    roles = db.relationship('Role', secondary=roles_users,
                            backref=db.backref('users', lazy='dynamic'))

and update the app configuration.

app.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = ('username','email')

Finally, create the custom login form.

from flask_security.forms import LoginForm
from wtforms import StringField
from wtforms.validators import InputRequired

class ExtendedLoginForm(LoginForm):
    email = StringField('Username or Email Address', [InputRequired()])

# Setup Flask-Security
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore,
                    login_form=ExtendedLoginForm)

Now, when logging in, Flask-Security will accept an email or username in the email form field.

I managed to implement login using either username or password by overwriting the login form:

class ExtendedLoginForm(LoginForm):
    email = StringField('Username or Email Address')
    username = StringField("Username")

    def validate(self):
    from flask_security.utils import (
        _datastore,
        get_message,
        hash_password,
    )
    from flask_security.confirmable import requires_confirmation
    if not super(LoginForm, self).validate():
        return False

    # try login using email
    self.user = _datastore.get_user(self.email.data)

    if self.user is None:
        self.user = _datastore.get_user(self.username.data)

    if self.user is None:
        self.email.errors.append(get_message("USER_DOES_NOT_EXIST")[0])
        # Reduce timing variation between existing and non-existing users
        hash_password(self.password.data)
        return False
    if not self.user.password:
        self.password.errors.append(get_message("PASSWORD_NOT_SET")[0])
        # Reduce timing variation between existing and non-existing users
        hash_password(self.password.data)
        return False
    if not self.user.verify_and_update_password(self.password.data):
        self.password.errors.append(get_message("INVALID_PASSWORD")[0])
        return False
    if requires_confirmation(self.user):
        self.email.errors.append(get_message("CONFIRMATION_REQUIRED")[0])
        return False
    if not self.user.is_active:
        self.email.errors.append(get_message("DISABLED_ACCOUNT")[0])
        return False
    return True

and register it as described in other posts:

# Setup Flask-Security
app.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = ('username','email')
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore,
                login_form=ExtendedLoginForm)

Since email and username are optional now one of them can be used to login. But make sure that both fields are set unique in the DB model.

In an extension, it’s possible

https://flask-security-too.readthedocs.io/en/stable/configuration.html

by this setting in config

SECURITY_USERNAME_ENABLE = True