这几行代码同样适用于所有其他弃用警告:

const db = await mongoose.createConnection(url, { useNewUrlParser: true });
mongoose.set('useCreateIndex', true);
mongoose.set('useFindAndModify', false);

下面突出显示的猫鼬连接代码解决了猫鼬驱动程序的警告:

mongoose.connect('mongodb://localhost:27017/test', { useNewUrlParser: true });

(node:16596) 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. (Use node --trace-deprecation ... to show where the warning was created) (node:16596) [MONGODB DRIVER] Warning: 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.

用法:

async connect(connectionString: string): Promise<void> {
        this.client = await MongoClient.connect(connectionString, {
    useUnifiedTopology: true,
    useNewUrlParser: true,
  })
        this.db = this.client.db()
}

更新为ECMAScript 8 / await

MongoDB公司提供的错误的ECMAScript 8演示代码也会产生此警告。

MongoDB提供了如下建议，不正确

要使用新的解析器，将选项{useNewUrlParser: true}传递给MongoClient.connect。

这样做将导致以下错误:

executeOperation的最终参数必须是一个回调

相反，这个选项必须提供给新的MongoClient:

请看下面的代码:

const DATABASE_NAME = 'mydatabase',
    URL = `mongodb://localhost:27017/${DATABASE_NAME}`

module.exports = async function() {
    const client = new MongoClient(URL, {useNewUrlParser: true})
    var db = null
    try {
        // Note this breaks.
        // await client.connect({useNewUrlParser: true})
        await client.connect()
        db = client.db(DATABASE_NAME)
    } catch (err) {
        console.log(err.stack)
    }

    return db
}

我使用mlab.com作为MongoDB数据库。我将连接字符串分离到一个名为config的不同文件夹，并在文件keys.js中保存连接字符串，这是:

模块导出 = { mongoURI：“mongodb://username:password@ds147267.mlab.com:47267/projectname” };

服务器代码是

const express = require("express"); const mongoose = require("mongoose"); const app = express(); // Database configuration const db = require("./config/keys").mongoURI; // Connect to MongoDB mongoose .connect( db, { useNewUrlParser: true } // Need this for API support ) .then(() => console.log("MongoDB connected")) .catch(err => console.log(err)); app.get("/", (req, res) => res.send("hello!!")); const port = process.env.PORT || 5000; app.listen(port, () => console.log(`Server running on port ${port}`)); // Tilde, not inverted comma

你需要像上面那样在连接字符串后面写{useNewUrlParser: true}。

简单地说，你需要做到:

猫鼬。connect(connectionString，{useNewUrlParser: true} / /或 MongoClient。connect(connectionString，{useNewUrlParser: true}

我们用的是:

mongoose.connect("mongodb://localhost/mean-course").then(
  (res) => {
   console.log("Connected to Database Successfully.")
  }
).catch(() => {
  console.log("Connection to database failed.");
});

这将给出一个URL解析器错误

正确的语法是:

mongoose.connect("mongodb://localhost:27017/mean-course" , { useNewUrlParser: true }).then(
  (res) => {
   console.log("Connected to Database Successfully.")
  }
).catch(() => {
  console.log("Connection to database failed.");
});