passport-local-mongoose中的"register“函数不起作用"User.register不是一个函数”

const mongoose = require('mongoose');
const passportLocalMongoose = require('passport-local-mongoose');

const UserSchema = new mongoose.Schema({
  // 定义用户模型的其他属性
});

UserSchema.plugin(passportLocalMongoose); // 将passport-local-mongoose插件与模型集成

const User = mongoose.model('User', UserSchema);

const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;

// 初始化Passport
app.use(passport.initialize());
app.use(passport.session());

// 使用Passport-Local策略
passport.use(new LocalStrategy(User.authenticate()));
passport.serializeUser(User.serializeUser());
passport.deserializeUser(User.deserializeUser());

User.register(new User({ username: 'username' }), 'password', function(err, user) {
  if (err) {
    // 处理错误
  } else {
    // 注册成功
  }
});