无法使用flask flask_login登录

app.secret_key = 'your_secret_key'

from flask_login import login_user

@app.route('/login', methods=['POST'])
def login():
    # 验证用户登录信息
    if valid_login(request.form['username'], request.form['password']):
        user = User(request.form['username'])
        login_user(user)
        return 'Logged in successfully!'
    else:
        return 'Invalid username or password'

from flask_login import UserMixin

class User(UserMixin):
    def __init__(self, id):
        self.id = id

    @staticmethod
    def get(id):
        # 根据用户ID获取用户对象
        return User(id)

from flask import render_template, request
from flask_login import login_user

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        # 验证用户登录信息
        if valid_login(request.form['username'], request.form['password']):
            user = User(request.form['username'])
            login_user(user)
            return 'Logged in successfully!'
        else:
            return 'Invalid username or password'
    else:
        return render_template('login.html')