为什么我会收到此错误“错误：已将握手入队后无法将握手入队。”？

Question

大家好，我只是想制作一个简单的表格，将数据发送到 mySQL 数据库。 我的问题是提交后无法再提交。 它只允许我提交一次表单，然后在第二次提交后我收到此错误“错误：已将握手入队后无法入队握手。” 我上网查了一下，好像每次表单提交后都需要重启到mysql的连接。 我试过放入 function，但似乎无法让它工作。

 //require packages var express = require("express"); var app = express(); var path = require("path"); var mysql = require("mysql"); var bodyParser = require("body-parser"); app.use(bodyParser.urlencoded({ extended: false })); app.use(bodyParser.json()); //connect to our database var con = mysql.createConnection({ host: "localhost", user: "root", password: "yourRootPassword", database: "mydb" }); //joining index.html to get route app.get("/", function(req, res) { res.sendFile(path.join(__dirname + "/index.html")); }); //setting post route to /submit >> how we post to database>> app.post("/submit", function(req, res) { //req.body.nameOfInput var name = req.body.name; var email = req.body.email; var username = req.body.username; res.write('You sent the name "' + req.body.name + '".\n'); res.write('You sent the email "' + req.body.email + '".\n'); res.write('You sent the username "' + req.body.username + '".\n'); //inserting data into sql var con.connect(function(err) { if (err) throw err; var sql = "INSERT INTO form (name, email,username) VALUES ('" + name + "', '" + email + "','" + username + "')"; con.query(sql, function(err, result) { if (err) throw err; console.log("1 record inserted"); res.end(); }); }); }); app.listen(3000); console.log("Running at Port 3000");

Answer 1

您正在连接多次，但没有关闭连接。 我使用连接池。 你这样做的方式可能会导致大量开放连接的建立，这将导致服务器宕机。 我也会做一个 res.status(200).send("Insert completed")，但看起来你有一些调试代码。

var myPool;
function connect() {
    return new Promise((resolve, reject) => {
        pool = mysql.createPool({
            connectionLimit: 10,
            host     : this.host,
            user     : this.user,
            password : this.password,
            database : this.database
        });
        resolve(pool);
    });
}

connect().then(pool => {
    myPool = pool;
})

app.post("/submit", function(req, res) {
  //req.body.nameOfInput
  var name = req.body.name;
  var email = req.body.email;
  var username = req.body.username;
  res.write('You sent the name "' + req.body.name + '".\n');
  res.write('You sent the email "' + req.body.email + '".\n');
  res.write('You sent the username "' + req.body.username + '".\n');
  //inserting data into sql var
  myPool.getConnection((err, con) => {
    if (err) throw err;
    var sql =
      "INSERT INTO form (name, email,username) VALUES ('" +
      name +
      "', '" +
      email +
      "','" +
      username +
      "')";
    con.query(sql, function(err, result) {
      if (err) throw err;
      console.log("1 record inserted");
      con.release();
      res.end();
    });
  });
});