実現したいこと

Flaskでの認証機能の実装に際して、ページにログイン必須の設定を行う。

発生しているエラー

ログイン必須の設定である@login_requiredをつけたページで
Missing user_loader or request_loaderというエラーが出る。

該当のソースコード

app.py
from pathlib import Path
from flask import Flask
from flask_login import LoginManager
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy
from flask_wtf.csrf import CSRFProtect

from apps.config import config

db = SQLAlchemy()
csrf = CSRFProtect()
login_manager = LoginManager()
login_manager.login_view = 'auth.signup'
login_manager.login_message = ''

def create_app(config_key):
    app = Flask(__name__)
    app.config.from_object(config_key)

    db.init_app(app)
    Migrate(app, db)
    csrf.init_app(app)
    login_manager.init_app(app)
    from apps.crud import views as crud_views
    app.register_blueprint(crud_views.crud, url_prefix='/crud')
    from apps.auth import views as auth_views
    app.register_blueprint(auth_views.auth, url_prefix='/auth')

    return app


if __name__ == '__main__':
    appp = create_app(config['Local'])
    appp.run(debug=True)

models.py
from datetime import datetime

from apps.app import db, login_manager
from flask_login import UserMixin
from werkzeug.security import generate_password_hash, check_password_hash


class User(db.Model, UserMixin):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String, index=True)
    email = db.Column(db.String, unique=True, index=True)
    password_hash = db.Column(db.String)
    created_at = db.Column(db.DateTime, default=datetime.now)
    updated_at = db.Column(
        db.DateTime, default=datetime.now, onupdate=datetime.now)

    @property
    def password(self):
        raise AttributeError('読み取り不可')

    @password.setter
    def password(self, password):
        self.password_hash = generate_password_hash(password)

    def verify_password(self, password):
        return check_password_hash((self.password_hash, password))

    def is_duplicate_email(self):
        return User.query.filter_by(email=self.email).first() is not None


@login_manager.user_loader
def load_user(user_id):
    return User.query.get(user_id)

views.py
from apps.crud.forms import UserForm
from flask import Blueprint, render_template, redirect, url_for
from flask_login import login_required
from apps.app import db
from apps.crud.models import User

crud = Blueprint(
    'crud',
    __name__,
    template_folder='templates',
    static_folder='static',
)


@crud.route('/')
@login_required
def index():
    return render_template('crud/index.html')


@crud.route('/sql')
@login_required
def sql():
    db.session.query(User).all()
    return 'コンソールログを確認してください'


@crud.route('/users/new', methods=['GET', 'POST'])
@login_required
def create_user():
    form = UserForm()
    if form.validate_on_submit():
        user = User(
            username=form.username.data,
            email=form.email.data,
            password=form.password.data,
        )
        db.session.add(user)
        db.session.commit()
        return redirect(url_for('crud.users'))
    return render_template('crud/create.html', form=form)


@crud.route('/users')
@login_required
def users():
    users = User.query.all()
    return render_template('crud/index.html', users=users)


@crud.route('/users/<user_id>', methods=['GET', 'POST'])
@login_required
def edit_user(user_id):
    form = UserForm()
    user = User.query.filter_by(id=user_id).first()
    if form.validate_on_submit():
        user.username = form.username.data
        user.email = form.email.data
        user.password = form.password.data
        db.session.add(user)
        db.session.commit()
        return redirect(url_for('crud.users'))

    return render_template('crud/edit.html', user=user,form=form)


@crud.route('/users/<user_id>/delete', methods=['POST'])
@login_required
def delete_user(user_id):
    user = User.query.filter_by(id=user_id).first()
    db.session.delete(user)
    db.session.commit()
    return redirect(url_for('crud.users'))