Mongoose Warning `open()` is deprecated, `openUri()` instead

nodejs 使用mongoose，程序如下：

const mongoose  = require('mongoose');
const url = `mongodb://192.168.1.198:27017/mean`

mongoose.connect(url) // default port 27017

錯誤如下：

DeprecationWarning: `open()` is deprecated in mongoose >= 4.11.0, use `openUri()` instead, or set the `useMongoClient` option if using `connect()` or `createConnection()`. See http://mongoosejs.com/docs/connections.html#use-mongo-client

解決方法：

mongoose.connect(url, {useMongoClient: true}) // default port 27017