몽고디비 대신 mysql을 사용했는데, 궁금한게 있습니다.

회사에서 node.js를 사용하기 위해 공부하는 직장인입니다.

회사에서 쓰기 위해서 영상을 공부하면서 몽고 DB 대신에 MYSQL로 검색을 통해 약간 수정해서 작업했습니다.

그런데, put이나 delet로 ajax로 전송해서 MYSQL로 SELCT 할 때 특히 오류가 나고(신기한 건 작동은 되는 것 같습니다. DB)

SELCT를 하는 list 페이지에서는 F5를 누르면  에러가 납니다.

일단 list 페이지의 오류 입니다.

node:events:498
throw er; // Unhandled 'error' event
^

Error: Cannot enqueue Handshake after already enqueuing a Handshake.
at Protocol._validateEnqueue (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:221:16)
at Protocol._enqueue (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:138:13)
at Protocol.handshake (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:51:23)
at Connection.connect (D:\node.js\node_modules\mysql\lib\Connection.js:116:18)
at D:\node.js\server.js:59:24
at Layer.handle [as handle_request] (D:\node.js\node_modules\express\lib\router\layer.js:95:5)
at next (D:\node.js\node_modules\express\lib\router\route.js:144:13)
at Route.dispatch (D:\node.js\node_modules\express\lib\router\route.js:114:3)
at Layer.handle [as handle_request] (D:\node.js\node_modules\express\lib\router\layer.js:95:5)
at D:\node.js\node_modules\express\lib\router\index.js:284:15
Emitted 'error' event on Connection instance at:
at Connection._handleProtocolError (D:\node.js\node_modules\mysql\lib\Connection.js:423:8)
at Protocol.emit (node:events:520:28)
at Protocol._delegateError (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:398:10)
at Handshake.<anonymous> (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:232:10)
at Handshake.emit (node:events:520:28)
at Handshake.Sequence.end (D:\node.js\node_modules\mysql\lib\protocol\sequences\Sequence.js:78:12)
at D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:236:14
at processTicksAndRejections (node:internal/process/task_queues:78:11) {
code: 'PROTOCOL_ENQUEUE_HANDSHAKE_TWICE',
fatal: false
}

Node.js v17.4.0
[nodemon] app crashed - waiting for file changes before starting...

두번쨰로 INSERT 전송시후 오류입니다. (전송자체는 성공했습니다.)

node:events:498
throw er; // Unhandled 'error' event
^

Error: Cannot enqueue Handshake after already enqueuing a Handshake.
at Protocol._validateEnqueue (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:221:16)
at Protocol._enqueue (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:138:13)
at Protocol.handshake (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:51:23)
at Connection.connect (D:\node.js\node_modules\mysql\lib\Connection.js:116:18)
at D:\node.js\server.js:44:20
at Layer.handle [as handle_request] (D:\node.js\node_modules\express\lib\router\layer.js:95:5)
at next (D:\node.js\node_modules\express\lib\router\route.js:144:13)
at Route.dispatch (D:\node.js\node_modules\express\lib\router\route.js:114:3)
at Layer.handle [as handle_request] (D:\node.js\node_modules\express\lib\router\layer.js:95:5)
at D:\node.js\node_modules\express\lib\router\index.js:284:15
Emitted 'error' event on Connection instance at:
at Connection._handleProtocolError (D:\node.js\node_modules\mysql\lib\Connection.js:423:8)
at Protocol.emit (node:events:520:28)
at Protocol._delegateError (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:398:10)
at Handshake.<anonymous> (D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:232:10)
at Handshake.emit (node:events:520:28)
at Handshake.Sequence.end (D:\node.js\node_modules\mysql\lib\protocol\sequences\Sequence.js:78:12)
at D:\node.js\node_modules\mysql\lib\protocol\Protocol.js:236:14
at processTicksAndRejections (node:internal/process/task_queues:78:11) {
code: 'PROTOCOL_ENQUEUE_HANDSHAKE_TWICE',
fatal: false
}

Node.js v17.4.0
[nodemon] app crashed - waiting for file changes before starting...

마지막으로 sever.js 코드입니다. connection의 내용은 지워두었습니다.

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

var mysql = require('mysql');
const { send } = require('express/lib/response');
var connection = mysql.createConnection({
  host     : '       ',    // 호스트 주소
  user     : '        ',           // mysql user
  password : '      ',       // mysql password
  database : '      ',         // mysql 데이터베이스
  charset : 'utf8',
  port: '      '
});
app.set('view engine','ejs');
app.engine('ejs', require('ejs').__express);
const methodOverride = require('method-override')
app.use(methodOverride('_method'))

const passport = require('passport')
const LocalStrategy = require('passport-local').Strategy
const session = require('express-session')

app.use(session({secret : '비밀코드',resave : true, saveUninitialized : false}));
app.use(passport.initialize())
app.use(passport.session())
app.listen(8080,function(){
    console.log(1)
    });
   

app.get('/%EC%A0%84%EC%86%A1',function(요청,응답){
    응답.sendFile(__dirname+'/send.html')
    });
app.post('/add',function(요청,응답){
        응답.send('전송')
        console.log(요청.body.title)
        console.log(요청.body.contents)

        let sql = 'INSERT INTO data (title,contents) VALUES ("'+요청.body.title+'","'+요청.body.contents+'")'
       
        connection.connect();
        connection.query(sql,
        function (에러, results, fields) {
           if(에러){console.log(에러)}
           
          console.log('전송');
       
        });
        connection.end();
       

        });
app.get('/list',function(요청,응답){
            let sql = 'SELECT * FROM data'
       
            connection.connect();
           connection.query(sql,
            function (에러, 결과, fields) {
               if(에러){console.log(에러)}
             
               응답.render('list.ejs',{posts:결과})
            });
           
           
});

app.delete('/delete',function(요청,응답){

  //  connection.connect();
let sql_del = 'DELETE FROM data WHERE idx = '+요청.body._idx
응답.send({result:'성공'});
connection.query(sql_del);

})

app.get('/edit/:id',function(요청,응답){

    let edit = 'SELECT * FROM data WHERE idx = '+요청.params.id
       console.log(edit)
    connection.connect();
   connection.query(edit,
    function (에러, 결과, fields) {
       if(에러){console.log(에러)}
      console.log(결과)
       응답.render('edit.ejs',{posts:결과})
    });
   
 
});

app.put('/edit',function(요청,응답){

    //  connection.connect();
  let sql_edit = 'UPDATE `data` SET `title`="'+요청.body.title+'",`contents`="'+요청.body.contents+'" WHERE idx='+요청.body.idx
  connection.query(sql_edit);
  응답.redirect('/list')
 
  })

  app.get('/login',function(요청,응답){

       응답.render('login.ejs')
 
});

app.post('/login',passport.authenticate('local',{failureRedirect : '/fail'}),function(요청,응답){
   
    응답.redirect('/')

    });

   
    passport.use(new LocalStrategy({
        usernameField: 'id',
        passwordField: 'pw',
        session: true,
        passReqToCallback: false,
      }, function (입력한아이디, 입력한비번, done) {
        //console.log(입력한아이디, 입력한비번);

       
        let member = 'SELECT id,pw FROM member WHERE id = "'+입력한아이디 +'" and pw = "'+입력한비번+'"'
        console.log(member)
       connection.connect();
    connection.query(member, function (에러, 결과, fields) {
      console.log(결과[0].id)
      console.log(결과[0].pw)
      let id = 결과[0].id
      let pw = 결과[0].pw

        if (에러) return done(에러)
       
        if (!id) return done(null, false, { message: '존재하지않는 아이디요' })
        if (입력한비번 == pw) {
          return done(null, 결과)
        } else {
          return done(null, false, { message: '비번틀렸어요' })
        }

     });

      }));