Flask login form

forms.py

class AuthenticationForm(Form):
    email = TextField()
    password = PasswordField()

    def validate_password(form, field):
        user = db.session.query(User).filter_by(email=form.email.data).first()
        if not user:
            raise ValidationError('Inccorect Email or Password combination')
        if not verify_and_update_password(field.data, user):
            raise ValidationError('Inccorect Email or Password combination')

        login_user(user)