如何通过pymongo和Flask-Login使用会话？

pip install pymongo
pip install Flask-Login

from flask import Flask, request, session, redirect, url_for
from flask_login import LoginManager, login_user, logout_user, login_required, current_user
from pymongo import MongoClient

app = Flask(__name__)
app.secret_key = 'your_secret_key'  # 设置Flask应用程序的密钥

client = MongoClient('mongodb://localhost:27017/')  # 连接MongoDB数据库
db = client['your_database_name']  # 替换为你的数据库名称

login_manager = LoginManager()
login_manager.init_app(app)

class User:
    def __init__(self, username):
        self.username = username

    def get_id(self):
        return self.username

@login_manager.user_loader
def load_user(username):
    user_data = db.users.find_one({'username': username})
    if user_data:
        return User(username=user_data['username'])
    return None

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        
        user_data = db.users.find_one({'username': username, 'password': password})
        if user_data:
            user = User(username=username)
            login_user(user)
            return redirect(url_for('index'))
        else:
            return 'Invalid username or password'
    
    return '''
    <form method="post" action="/login">
        <input type="text" name="username" placeholder="Username" required><br>
        <input type="password" name="password" placeholder="Password" required><br>
        <input type="submit" value="Login">
    </form>
    '''

@app.route('/logout')
@login_required
def logout():
    logout_user()
    return redirect(url_for('index'))

@app.route('/')
@login_required
def index():
    return 'Welcome, {}'.format(current_user.username)

if __name__ == '__main__':
    app.run()