MongooseError：` `openUri()`的`uri`参数必须为字符串

Question

我的代码有一个问题，我在app.js中使用了以下代码：

const mongoose = require('mongoose'); 
const dotenv = require('dotenv'); 
dotenv.config()

  mongoose.connect(process.env.MONGO_URL) 
.then(() => console.log("DB connected!"));

    mongoose.connection.on('error',function(err){   
console.log("The error is: ");
});

env.txt：

MONGO_URL=mongodb+srv://blur:blur@nodeapi-pfnvf8.mongodb.net/test?retryWrites=true
PORT:8080

出于某种原因，它给了我一个奇怪的错误：

throw new MongooseError('The `uri` parameter to `openUri()` must be a ' +
    ^ MongooseError: The `uri` parameter to `openUri()` must be a string, got "undefined". Make sure the first parameter to `mongoose.connect()` or `mongoose.createConnection()` is a string.
    at new MongooseError (C:\Users\razei\Desktop\Recat\project2\node_modules\mongoose\lib\error\mongooseError.js:14:11)
    at NativeConnection.Connection.openUri (C:\Users\razei\Desktop\Recat\project2\node_modules\mongoose\lib\connection.js:465:11)
    at Mongoose.connect (C:\Users\razei\Desktop\Recat\project2\node_modules\mongoose\lib\index.js:289:15)
    at Object.<anonymous> (C:\Users\razei\Desktop\Recat\project2\ap.js:9:10)
    at Module._compile (internal/modules/cjs/loader.js:701:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:754:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3) [nodemon] app crashed - waiting for file changes before starting...

有人能帮帮我吗?我看了几篇文章，但都没帮上忙

Answer 1

当您没有将.env文件保存在根文件夹中时，也会发生这种情况。

Answer 2

将您的环境文件保存为.env，而不是env.txt，并确保它也在您的根文件夹中&看看这是否有效！此外，MONGO_URI是传统的命名约定，但这无关紧要。

mongoose
    .connect(process.env.MONGO_URL, {
        useNewUrlParser: true,
        useCreateIndex: true,
        useUnifiedTopology: true
    })
    .then(() => {
        console.log('Connected to Mongo!');
    })
    .catch((err) => {
        console.error('Error connecting to Mongo', err);
    });

另外，你可以用下面的几行代码来简化上面的2条require语句，你应该尽快调用它：

require('dotenv').config();
const mongoose = require('mongoose')

Answer 3

需要这样的dotenv。这对我很管用

require('dotenv').config();