find mongodb数据库的toArry docs 显示undefined

var express = require('express');
var router = express.Router();
var model=require('../model');
/* GET home page. */
router.get('/', function(req, res, next) {
model.connect(function(db){
db.collection('users').find().toArray(function(err,docs){
console.log('用户列表', docs) //j就是这里的错误 docs是undefined

res.render('index', { title: 'Express' });
})
})
});

mongodb find()查询的结果就是array类型，不用toArray

先定义
docs
var docs;