一、使用mongoose链接数据库

'use strict';const mongoose = require('mongoose');const config = require('config-lite')({    filename: 'default',    config_basedir: __dirname,    config_dir: 'config'});const chalk = require('chalk');mongoose.connect(config.url, { dbName: config.db, useNewUrlParser: true, autoIndex: false });const connect = mongoose.connection;connect.once('open', () => {    console.log(        chalk.green('connect db success！')    );})connect.on('error', function (error) {    console.error(        chalk.red('Error in MongoDb connection: ' + error)    );    mongoose.disconnect();});connect.on('close', function () {    console.log(        chalk.red('the db is disconnect ,reconnect...')    );    mongoose.connect(config.url, { server: { autoReconnect: true } });});module.exports = connect;

　二、新建一个store.js文件

const { Store } = require('koa-session2');module.exports = class extends Store {    constructor(con) {        super();        this.collection = con.collection('sessions');        console.log("session start ");    }    async get(sid) {        return await this.collection.findOne({ sid });    }    async set(session, opts) {        try {            if (!opts.sid) {                opts.sid = this.getID(24);            }            await this.collection.findOneAndUpdate({ sid: opts.sid }, { $set: session }, { upsert: true });        } catch (error) {            console.log("error", error);        }        return opts.sid;    }    async destory(sid) {        await this.collection.findAndModify({ sid }, [], {}, { removed: true });    }}

　　

三、在app.js中

const session = require("koa-session2");const sessionStore = require('./middlewares/seesionStore/store');app.use(session({  key: config.session.key,  maxAge: config.session.maxAge,  domain: config.session.domain,  store: new sessionStore(connect)}));