Flask. Why does it throw a TypeError when trying to write data to the database?

Question

Flask

Hello.
I'm trying to get to grips with flask and writing a small blog app.
Now I am registering users and when I try to enter data into the database, an error is generated

TypeError: add() missing 1 required positional argument: 'instance'

Error Screen:
Here is the code: file

app/models.py

from werkzeug.security import generate_password_hash, check_password_hash
from app import db
from config import ROLE_USER


class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    role = db.Column(db.SmallInteger, default=ROLE_USER.get('user'))
    email = db.Column(db.String(120), index=True, unique=True)
    pwd_hash = db.Column(db.String(100))
    nickname = db.Column(db.String(64), index=True, unique=True)
    about_me = db.Column(db.Text)
    last_seen = db.Column(db.DateTime)
    posts = db.relationship('Post', backref='author', lazy='dynamic')
    comments = db.relationship('Comment', backref='author', lazy='dynamic')

    @property
    def is_authenticated(self):
        return True

    @property
    def is_active(self):
        return True

    @property
    def is_anonymous(self):
        return False

    @property
    def get_id(self):
        return str(self.id)

    def set_password(self, password):
        self.pwd_hash = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.pwd_hash, password)

    def __init__(self, nickname, email, password):
        self.nickname = nickname
        self.email = email
        self.set_password(password)

    def __repr__(self):
        return '<User %r>' % self.nickname

File

/app/views.py

from flask import render_template, redirect, url_for, flash, request
from .forms import LoginForm, RegisterForm
from .models import User, Post
from app import app, db


@app.route('/')
def index():
    text = 'Home Page'
    return render_template('index.html',
                           text=text)

@app.route('/signup', methods=['GET', 'POST'])
def create_user():
    form = RegisterForm()
    if form.validate_on_submit():
        new_user = User(form.nickname.data, form.email.data, form.password.data)
        db.Session.add(new_user)
        db.Session.commit()
        return redirect(url_for('index'))
    return render_template('register.html',
                           title='Sign Up',
                           form=form)

Answer 1

Isn't it db.session.add()instead db.Session.add()?
And further:

new_user = User(nickname=form.nickname.data, email=form.email.data, pwd_hash=form.password.data)