如何在nodejs中正确连接mysql？答案

【问题标题】：How to connect to mysql properly in nodejs?如何在nodejs中正确连接mysql？
【发布时间】：2016-12-12 04:59:04
【问题描述】：

我在这里尝试做的是查询 mysql 数据库，但是当我执行我的查询时，它只是永远加载，直到超时都没有错误，如何解决这个问题？下面是我的 db.js 代码：

Db.js：

var mysql = require("mysql");
var settings = require("../settings");

    exports.executeSql = function (sql, callback) {
        var conn = new mysql.createConnection(settings.dbConfig);
        conn.connect(function(err){
            if(err){
                console.log(err + "1");
                return;
            }

            console.log(conn.log + "2");
        })

};

这是我的 bassCtrl.js：

var db = require("../core/db");
var httpMsgs = require("../core/httpMsgs");

    exports.get_user = function(req, resp) {


        db.executeSql("select * from mst_user", function(data, err) {
            console.log("in controller");
            if (err) {
                httpMsgs.show500(req, resp, err);
            } else {
                httpMsgs.sendJson(req, resp, data);
            };
        });
};

这是我的 routes.js

var express = require('express');
var bassCtrl = require("../controllers/bassCtrl");
var httpMsgs = require("../core/httpMsgs");
var jwt = require('jsonwebtoken');

module.exports = function(app, express) {
    var router = express();

    router.route('/get_user').get(bassCtrl.get_user);


return router;
};

下面是我的 HttpMsgs.js ：

var settings = require("../settings");

exports.show500 = function(req, resp, err) {
    if (settings.httpMsgsFormat === 'HTML') {
        resp.writeHead(500, "Internal Error occuared", {"Content-Type":"text/html"});
        resp.write("<html><head><title>500</title></head><body>500: Internal Error. Details: " + err + "</body></html>");
    } else {
        resp.writeHead(500, "Internal Error occuared", {"Content-Type":"application/json"});
        resp.write(JSON.stringify({ data: "Error occurred: " + err }));
    }
    resp.end();
}

exports.sendJson = function(req, resp, data) {
    resp.writeHead(200, {"Content-Type":"application/json"});
    if (data) {
        resp.write(JSON.stringify(data));
    }
    resp.end();
}

exports.show405 = function(req, resp) {
    if (settings.httpMsgsFormat === 'HTML') {
        resp.writeHead(405, "Method not supported", {"Content-Type":"text/html"});
        resp.write("<html><head><title>405</title></head><body>405: Method not supported.</body></html>");
    } else {
        resp.writeHead(405, "Method not supported", {"Content-Type":"application/json"});
        resp.write(JSON.stringify({ data: "Method not supported"}));
    }
    resp.end();
}

exports.show413 = function(req, resp) {
    if (settings.httpMsgsFormat === 'HTML') {
        resp.writeHead(404, "Resource not found", {"Content-Type":"text/html"});
        resp.write("<html><head><title>413</title></head><body>404: Resource not found.</body></html>");
    } else {
        resp.writeHead(404, "Resource not found", {"Content-Type":"application/json"});
        resp.write(JSON.stringify({ data: "Resource not found"}));
    }
    resp.end();
}

exports.show413 = function(req, resp) {
    if (settings.httpMsgsFormat === 'HTML') {
        resp.writeHead(413, "Request Entity Too Large", {"Content-Type":"text/html"});
        resp.write("<html><head><title>413</title></head><body>413: Request Entity Too Large.</body></html>");
    } else {
        resp.writeHead(413, "Request Entity Too Large", {"Content-Type":"application/json"});
        resp.write(JSON.stringify({ data: "Request Entity Too Large"}));
    }
    resp.end();
}

exports.send200 = function(req, resp) {
    resp.writeHead(200, {"Content-Type":"application/json"});
    resp.write(JSON.stringify(
        {status: "success", code: 200}
    ));
    resp.end();
}

exports.showHome = function(req, resp) {
    if (settings.httpMsgsFormat === 'HTML') {
        resp.writeHead(200, {"Content-Type":"text/html"});
        resp.write("<html><head><title>200</title></head><body>Your server connected dude ! :)</body></html>");
    } else {
        resp.writeHead(200, {"Content-Type":"application/json"});
        resp.write(JSON.stringify(
            {status: "Your server connected dude ! :)"}
        ));
    }
    resp.end();
}

这是我的 settings.js：

exports.dbConfig = {
    user: "root",
    password: "",
    host: "localhost",
    database: "zouk"
};

exports.httpMsgsFormat = "json";

当我触发 localhost:5000/get_user 时，它只是加载直到超时，我的 console.log 打印此行 console.log(connection.log + "2"); 并以 undefined 作为值。有什么我想念的吗？

等一下，为什么我的问题评分为负？

【问题讨论】：

标签： javascript mysql node.js database-connection

【解决方案1】：

您没有在 Db.js 文件中执行查询，并且您的代码也没有调用回调，这就是它运行到超时的原因。

var connection = mysql.createConnection({
  host     : ***,
  user     : ***,
  password : ***,
  database : ***,
});

connection.connect();

connection.query(sql, function(err, rows, fields) {
  if (err) throw err;

  console.log('The solution is: ', rows[0].solution);
  //your callback go here.
  // callback(rows);//pass whatever you need in.
});

connection.end();

另外，您的控制器不需要httpMsgs。我觉得应该有。

【讨论】：

是的，我已经执行了我的 db.js 文件，我只是取消了名为 bassCtrl.js 的控制器文件的日期。我在这一行执行它 db.executeSql("select * from mst_user", function(err, rows, fields)
您可以尝试使用 httpMsgs 跳过并直接使用 resp。在流程的每个步骤中使用console.log 进行观察。