몽고디비연결시 에러문제

[박진석]

const express = require('express')
app.use(express.urlencoded({ extended: true }));
const app = express()
const MongoClient = require('mongodb').MongoClient

MongoClient.connect('mongodb+srv://admin:qwer@cluster0.ewoewop.mongodb.net/todoapp?retryWrites=true&w=majority', function(에러, client){
  
  app.listen(8080, function() {
    console.log('listening on 8080')
  })
})


이렇게 실행했는데 자꾸

에러가 나옵니다..

[nodemon] restarting due to changes...
[nodemon] starting `node server.js`
C:\Users\user\Desktop\todoapp\server.js:2
app.use(express.urlencoded({ extended: true }));
^

ReferenceError: Cannot access 'app' before initialization
    at Object.<anonymous> (C:\Users\user\Desktop\todoapp\server.js:2:1)
    at Module._compile (node:internal/modules/cjs/loader:1126:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1180:10)
    at Module.load (node:internal/modules/cjs/loader:1004:32)
    at Function.Module._load (node:internal/modules/cjs/loader:839:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:17:47
[nodemon] app crashed - waiting for file changes before starting...

[박진석]

상단 코드에

const MongoClient = require('mongodb')

mongodb 이부분에 마우스를 갖다대면 

모듈 'mongodb'에 대한 선언 파일을 찾을 수 없습니다. 'C:/Users/user/Desktop/todoapp/node_modules/mongodb/index.js'에는 암시적으로 'any' 형식이 포함됩니다.
 해당 항목이 있는 경우 'npm i --save-dev @types/mongodb'을(를) 시도하거나, 'declare module 'mongodb';'을(를) 포함하는 새 선언

이게 뜹니다..

[codingapple]

npm install mongodb 하셨나요
app.use(express 어쩌구는 더 밑으로 옮깁시다 

[박진석]

몽고디비 언인스톨 하고 다시 깔았는데도 안되네요 .. 하ㅜ

ReferenceError: Cannot access 'app' before initialization
    at Object.<anonymous> (C:\Users\user\Desktop\todoapp\server.js:4:1)
    at Module._compile (node:internal/modules/cjs/loader:1126:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1180:10)
    at Module.load (node:internal/modules/cjs/loader:1004:32)
    at Function.Module._load (node:internal/modules/cjs/loader:839:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:17:47
[nodemon] app crashed - waiting for file changes before starting...

[codingapple]

app.어쩌구는 
const app = express() 밑에있어야합니다

[박진석]

에러가 계속 뜨는데흠... npm install mongodb@3.6.4를 하면 require('mongo')
밑에 점이 생겨요 이게 원인일까요?

[박진석]

const express = require('express');
const app = express();
app.use(express.urlencoded({extended: true}));

const MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb+srv://admin:qwer1234@cluster0.v62mpib.mongodb.net/?retryWrites=true&w=majority', function(에러, client){
    if (에러) return console.log(에러);
    app.listen('8080', function(){
      console.log('listening on 8080')
    });
  })

app.listen(8080, function(){
    console.log('listening on 8080')
});

app.get('/pet', function(요청, 응답){
    응답.send('펫용품 쇼핑할 수 있는 페이지입니다.');
});

app.get('/beauty', function(요청, 응답){
    응답.send('뷰티용품 쇼핑할 수 있는 페이지입니다.');
});

app.get('/', function(요청, 응답){
    응답.sendFile(__dirname + '/index.html')
});

app.get('/write', function(요청, 응답){
    응답.sendFile(__dirname + '/write.html')
});

app.post('/add', function(요청, 응답){
    응답.send('전송완료')
    console.log(요청.body.title)
});

터미널에 오류가 이런식으로 나옵니다.

[nodemon] 2.0.19
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node server.js`
listening on 8080
node:events:491
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE: address already in use :::8080
    at Server.setupListenHandle [as _listen2] (node:net:1432:16)        
    at listenInCluster (node:net:1480:12)
    at Server.listen (node:net:1568:7)
    at Function.listen (C:\Users\user\Desktop\todoapp\node_modules\express\lib\application.js:635:24)
    at C:\Users\user\Desktop\todoapp\server.js:9:9
    at C:\Users\user\Desktop\todoapp\node_modules\mongodb\lib\utils.js:371:9
    at C:\Users\user\Desktop\todoapp\node_modules\mongodb\lib\mongo_client.js:138:17
    at connectCallback (C:\Users\user\Desktop\todoapp\node_modules\mongodb\lib\operations\connect.js:29:9)
    at C:\Users\user\Desktop\todoapp\node_modules\mongodb\lib\operations\connect.js:81:9
    at C:\Users\user\Desktop\todoapp\node_modules\mongodb\lib\sdam\topology.js:203:73
Emitted 'error' event on Server instance at:
    at emitErrorNT (node:net:1459:8)
    at processTicksAndRejections (node:internal/process/task_queues:83:21) {
  code: 'EADDRINUSE',
  errno: -4091,
  syscall: 'listen',
  address: '::',
  port: 8080
}

[codingapple]

8080에 이미 떠있다는뜻인데 에디터 다 끄고 다시 시작하면 잘됩니다

[박진석]

감사합니다 추석연휴잘보내십쇼 센세~.~

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