mongoose mpromise被废弃警告，(node:3341) DeprecationWarning: Mongoose: mpromise (mongoose's default promis

在使用mongoose的时候，报出如下错误：

DeprecationWarning: Mongoose: mpromise (mongoose's default promise library) is deprecated, plug in your own promise library instead: http://mongoosejs.c om/docs/promises.html

Mongoose 做异步操作时，为了向后兼容，Mongoose 4 默认使用mpromise 作为返回值。mpromise已被废弃，推荐使用 ES6风格的 promises库或者ES6原生的Promise库

调用mongoose.connect使用Promise方式

原生的ES6 Promise

mongoose.Promise = global.Promise;
mongoose.connect('mongodb://localhost:27107/data/db');

bluebird promise(使用蓝鸟承诺库)

var uri = 'mongodb://localhost:27017/data/db';
var options = { promiseLibrary: require('bluebird') };
var db = mongoose.createConnection(uri, options);