前言

今天在根据mongoose中文文档链接数据库时候，发现报了2个错误，百度查了一下，使用connect连接数据库时候必须配置{useNewUrlParser:true,useUnifiedTopology: true}

问题

const mongoose = require('mongoose');
const db= mongoose.connection;
const dbAddress='mongodb://localhost/douban';
mongoose.Promise=global.Promise
exports.connect=()=>{
    if(process.env.NODE_ENV !=='production'){
        mongoose.set('debug',true);
    }
    mongoose.connect(dbAddress);
    db.once('open',()=>{
        console.log('mongodb connect successly')
    });
    db.on('error',err=>{
        console.log(err);
    });
}
//(node:3960) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
//(node:3960) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.  

解决方案：

const mongoose = require('mongoose');
const db= mongoose.connection;
const dbAddress='mongodb://localhost/douban';
mongoose.Promise=global.Promise
exports.connect=()=>{
    if(process.env.NODE_ENV !=='production'){
        mongoose.set('debug',true);
    }
    mongoose.connect(dbAddress, {useNewUrlParser:true,useUnifiedTopology: true});
    db.once('open',()=>{
        console.log('mongodb connect successly')
    });
    db.on('error',err=>{
        console.log(err);
    });
}

总结

看来还是看官方文档最靠谱，中文文档更新有些迟缓了。