javascript - 未处理的PromiseRejection警告: MongooseServerSelectionError

Question

我正在学习这些教程，因为我想从 MongoDB 和 MERN 堆栈开始:

• https://medium.com/@beaucarnes/learn-the-mern-stack-by-building-an-exercise-tracker-mern-tutorial-59c13c1237a1
• https://www.youtube.com/watch?v=7CqJlxBYj-M

一切都很好，直到我与数据库的连接失败。我检查了用户名/密码一百万次，我复制并粘贴了原始内容，以防出现语法错误。这是错误:

(node:10156) UnhandledPromiseRejectionWarning: MongooseServerSelectionError: connection <monitor> to 34.249.129.6:27017 closed
    at new MongooseServerSelectionError (C:\Users\Mario\Desktop\ReactProject\MongoDB\mern-tracker\node_modules\mongoose\lib\error\serverSelection.js:22:11)
    at NativeConnection.Connection.openUri (C:\Users\Mario\Desktop\ReactProject\MongoDB\mern-tracker\node_modules\mongoose\lib\connection.js:808:32)
    at Mongoose.connect (C:\Users\Mario\Desktop\ReactProject\MongoDB\mern-tracker\node_modules\mongoose\lib\index.js:333:15)
    at Object.<anonymous> (C:\Users\Mario\Desktop\ReactProject\MongoDB\mern-tracker\server\server.js:51:10)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)
(node:10156) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:10156) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

这是我的 server.js:

const express = require("express");
const mongoose = require("mongoose");
require("dotenv").config();
const app = express();

const port = process.env.PORT || 5000;

app.use(cors());
app.use(express.json());

const uri = process.env.ATLAS_URI;



mongoose.connect(uri, {
  useNewUrlParser: true,
  useCreateIndex: true,
  useUnifiedTopology: true
});

const connection = mongoose.connection;
// connection.on("error", error => console.error(error));
connection.once("open", uri => {
  console.log("MongoDB database connections established");
});

const exercisesRoute = require("./routes/exercises");
const usersRoute = require("./routes/users");

app.use("./exercises", exercisesRoute);
app.use("./users", usersRoute);

app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});

由于错误是关于未处理的 promise ，所以我在 Mongoose 连接中也尝试过的是:

  mongoose
    .connect(uri, {
      useNewUrlParser: true,
      useCreateIndex: true,
      useUnifiedTopology: true
    })
    .catch(err => {
      console.log(Error, err.message);
    })
    .then(() => console.log("DB Connected!"))

这给了我下一个错误:

{ [Function: Error] stackTraceLimit: 16, prepareStackTrace: undefined } 'connection <monitor> to 52.212.0.151:27017 closed'
DB Connected!

但尚未连接。

有时在错误中，connection <monitor> to 52.212.0.151:27017 closed'更改为34.249.129.6:27017

我尝试的另一件事是删除集群并创建一个新集群，但发生了同样的事情我使用的是 Windows 和 Node v10.16.3

希望大家能帮助我或给我建议。

Answer 1

试试这个看来您正在使用 MongoDB atlas

mongoose
     .connect( uri, { useNewUrlParser: true, useCreateIndex: true, useUnifiedTopology: true })
     .then(() => console.log( 'Database Connected' ))
     .catch(err => console.log( err ));

然后转到您的MongoDB Atlas -> NetworkAccess-> 编辑->并添加当前IP地址它可以工作!!