Node.js从MongoDB获取数据持续超时错误的排查求助

我正在搭建一个网站，前端使用React.js，后端使用Node.js，数据库采用MongoDB。我在数据库中存入了一些测试数据，使用Express和Mongoose进行开发，在Atlas上创建了数据库，数据库连接显示成功，但在浏览器访问localhost:5000/Companies获取集合数据时，始终返回连接超时错误。

我的代码文件： #

server.js

const express=require('express')
const { connectDB,disconnectDB  } = require('./db');
const cors = require('cors');
const Company = require('./models/Company');

var app = express();

// Enable CORS for specific origins
app.use(cors({
    origin: 'http://localhost:3000' // Allow requests from http://localhost:3000
}));

app.get("/api",(req,res)=>{
    res.json({"users":["user1","user2", "user3"]})
})

app.get("/Companies",async (request,response)=>{
    try {
        // Connect to MongoDB (if not already connected)
        await connectDB();

        // Fetch all companies from the companies collection
        const companies = await Company.find();
        
        // Send the list of companies as a JSON response
        response.json(companies);
    } catch (error) {
        // Handle errors
        console.error('Error fetching companies:', error);
        response.status(500).json({ error: 'Internal Server Error' });
    }
})

app.listen("5000",()=>{
    console.log("Server is running on port 5000")
});

// Handle graceful shutdown
process.on('SIGINT', async () => {
    try {
        await disconnectDB();
        console.log('Disconnected from MongoDB');
        process.exit(0);
    } catch (error) {
        console.error('Error disconnecting from MongoDB:', error);
        process.exit(1);
    }
});

models/Company.js

// models/Company.js

const mongoose = require('mongoose');

// Define the schema for the Company collection
const companySchema = new mongoose.Schema({
    "_company_name": String,
    "_link": String
    // You can define other fields as needed
});

// Create a Mongoose model for the Company collection
const Company = mongoose.model('companies', companySchema);

module.exports = Company;

db.js

// db.js
const mongoose = require('mongoose');

require('dotenv').config();

const connectDB = async () => {
   
   try {
       await mongoose.connect('mongodb://localhost:27017/Zien', {
       });
       console.log('db connection success');
   } catch (error) {
       console.error('Error connecting to MongoDB:', error);
   }
};

const disconnectDB = async () => {
   try {
       await mongoose.disconnect();
       console.log('Disconnected from MongoDB');
   } catch (error) {
       console.error('Error disconnecting from MongoDB:', error);
   }
};

module.exports = { connectDB, disconnectDB };

已尝试的操作及错误： #

• 切换本地MongoDB和Atlas连接字符串，均出现相同超时错误
• 使用limit(10)减少单次获取的文档数量，仍无响应且超时，控制台报错：

Error fetching companies: MongooseError: Operation companies.find() buffering timed out after 10000ms
at Timeout. (D:\backend\node_modules\mongoose\lib\drivers\node-mongodb-native\collection.js:186:23)
at listOnTimeout (node:internal/timers:573:17)
at process.processTimers (node:internal/timers:514:7)

• 尝试使用toArray()转换查询结果，控制台报错：

Error fetching companies: TypeError: Company.find(...).limit(...).toArray is not a function
at D:\xampp\htdocs\employerrating\application\views\modules\zien-backend\server.js:33:56

解决方案 #

问题已解决，将connectDB调用移至app.listen的回调函数中，修改后的代码如下：

app.listen("5000",async ()=>{
    try {
        await connectDB();
        console.log("Server is running on port 5000")
    } catch (error) {
        console.error("Error starting server:", error);
    }
});

问题原因是之前每次请求/Companies接口时都会尝试连接数据库，现在调整为服务器启动时就完成数据库连接，避免了重复连接导致的超时问题。

内容的提问来源于stack exchange，提问作者amalu