How do you pass and execute a mysql query? - javascript

I was wondering how to execute a mysql query so that the client can see like "users registered: number"
Server.js:
var http = require('http');
var ejs = require('ejs');
var fs = require('fs');
var mysql = require('mysql');
var connection = mysql.createConnection({
host: '127.0.0.1',
user: 'root',
password: 'root',
database: 'kitsune',
connectionLimit: 50,
port: 3306 });
connection.connect(function(err) {
if (err) throw err;
});
connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
if (error) throw error;
console.log('The solution is: ', results[0].solution);
});
module.exports = connection;
http.createServer(function(req,res) {
res.writeHead(200, {'Content-Type': 'text/html'});
fs.readFile('index.html', 'utf-8', function(err, content) {
if (err) {
res.end('error occurred');
return;
}
var countQuery = "SELECT Count(ID) AS NumberOfPenguins FROM Penguins"; console.log(countQuery);
connection.query(countQuery, function(err, rows) {
if (err) throw err;
console.log('Connected!');
});
var renderedHtml = ejs.render(content, {countQuery: countQuery});
res.end(renderedHtml);
});
}).listen(80);
index.html:
<html>
<head>
</head>
<body>
Users registered: <%= countQuery %>
</body>
</html>
This only shows the query but it does not execute it. Any idea on how to execute it?


You executed the query sure but you never did anything with the results. The result is the rows passed in the callback function.
connection.query(countQuery, function(err, rows) {
if (err) throw err;
var renderedHtml = ejs.render(content, {countQuery: rows});
res.end(renderedHtml);
});

Related

i got Node.js MySQL - Error: connect ECONNREFUSED

i got the above error
my code was like this
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "username",
password: "password",
socketPath: "/Applications/MAMP/tmp/mysql/mysql.sock"
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
con.query("CREATE DATABASE mydb", function (err, result) {
if (err) throw err;
console.log("Database created");
});
});
con.end();
i tried to do as they explain in the below link but i did not know how to find my socket path?
enter link description here

How to merge two files API (Node.js)

I am a node.js and MySQL beginner and I just started setting up and trying out some basic code.
I find these two APIs to practice, one is the API for the CRUD database, and the other is the API for judging user login / registration.I tried to merge the APIs of these two files, and the result was a problem. I think the current problem is the configuration file (conf.js).I plan to write a function and then wrap any file and use it again, so that the configuration files may not conflict, but I don’t know how to start.
These are the two API teaching URLs I practiced
http://www.expertphp.in/article/user-login-and-registration-using-nodejs-and-mysql-with-example
https://www.footmark.info/programming-language/nodejs/nodejs-restful-webapi-mysql/
index.js
var express = require("express");
var bodyParser = require("body-parser");
var app = express();
var authenticateController = require("./controllers/authenticate-controller");
var registerController = require("./controllers/register-controller");
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.post("/api/register", registerController.register);
app.post("/api/authenticate", authenticateController.authenticate);
app.listen(3000);
app.js
var bodyparser = require("body-parser");
var express = require("express");
var conf = require("./conf");
var functions = require("./functions");
var user = require("./routes/user");
var app = express();
req.body
app.use(bodyparser.urlencoded({ extended: false }));
app.use(bodyparser.json());
//app.use(functions.passwdCrypto);
app.use("/user", user);
app.listen(conf.port, function() {
console.log("app listening on port " + conf.port + "!");
});
authenticate-controller.js
var connection = require('./../conf');
module.exports.authenticate=function(req,res){
var email=req.body.email;
var password=req.body.password;
connection.query('SELECT * FROM user WHERE email = ?',[email], function (error, results, fields) {
if (error) {
res.json({
status:false,
message:'there are some error with query'
})
}else{
if(results.length >0){
if(password==results[0].password){
res.json({
status:true,
message:'successfully authenticated'
})
}else{
res.json({
status:false,
message:"Email and password does not match"
});
}
}
else{
res.json({
status:false,
message:"Email does not exits"
});
}
}
});
}
register-controller.js
var connection = require('../conf');
module.exports.register=function(req,res){
var today = new Date();
var user={
"name":req.body.name,
"email":req.body.email,
"password":req.body.password,
"created_at":today,
"updated_at":today
}
connection.query('INSERT INTO user SET ?',user, function (error, results, fields) {
if (error) {
res.json({
status:false,
message:'there are some error with query'
})
}else{
res.json({
status:true,
data:results,
message:'user registered sucessfully'
})
}
});
}
user.js(models)
var mysql = require("mysql");
var conf = require("../conf");
var connection = mysql.createConnection(conf.db);
var sql = "";
module.exports = {
items: function(req, callback) {
sql = "SELECT * FROM user";
return connection.query(sql, callback);
},
item: function(req, callback) {
sql = mysql.format("SELECT * FROM user WHERE userId = ?", [req.params.id]);
return connection.query(sql, callback);
},
add: function(req, callback) {
sql = mysql.format("INSERT INTO user SET ?", req.body);
return connection.query(sql, callback);
},
delete: function(req, callback) {
sql = mysql.format("DELETE FROM user WHERE userId = ?", [req.params.id]);
return connection.query(sql, callback);
},
put: function(req, callback) {
connection.beginTransaction(function(err) {
if (err) throw err;
sql = mysql.format("DELETE FROM user WHERE userId = ?", [req.params.id]);
connection.query(sql, function(err, results, fields) {
if (results.affectedRows) {
req.body.id = req.params.id;
sql = mysql.format("INSERT INTO user SET ?", req.body);
connection.query(sql, function(err, results, fields) {
if (err) {
connection.rollback(function() {
callback(err, 400);
});
} else {
connection.commit(function(err) {
if (err) callback(err, 400);
callback(err, 200);
});
}
});
} else {
callback(err, 410);
}
});
});
},
patch: function(req, callback) {
sql = mysql.format("UPDATE user SET ? WHERE userId = ?", [req.body, req.params.id]);
return connection.query(sql, callback);
}
};
user.js(routes)
var express = require("express");
var user = require("../models/user");
var router = express.Router();
router
.route("/")
.get(function(req, res) {
user.items(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.length) {
res.sendStatus(404);
return;
}
res.json(results);
});
})
.post(function(req, res) {
user.add(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
res.status(201).json(results.insertId);
});
});
router
.route("/:id")
.get(function(req, res) {
user.item(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.length) {
res.sendStatus(404);
return;
}
res.json(results);
});
})
.delete(function(req, res) {
user.delete(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.affectedRows) {
res.sendStatus(410);
return;
}
res.sendStatus(204);
});
})
.put(function(req, res) {
user.put(req, function(err, results) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (results === 410) {
res.sendStatus(410);
return;
}
user.item(req, function(err, results, fields) {
res.json(results);
});
});
})
.patch(function(req, res) {
user.patch(req, function(err, results, fields) {
if (err) {
res.sendStatus(500);
return console.error(err);
}
if (!results.affectedRows) {
res.sendStatus(410);
return;
}
req.body.id = req.params.id;
res.json([req.body]);
});
});
module.exports = router;
conf.js
var mysql = require("mysql");
var connection = mysql.createConnection({
host: "localhost",
user: "root",
password: "1234",
database: "farmbot",
});
connection.connect(function(err) {
if (!err) {
console.log("Database is connected");
} else {
console.log("Error while connecting with database");
}
});
module.exports = connection;
/*If I comment out the code below, I can execute the login / register API*/
/*Without commenting out, can only perform CRUD on the database*/
module.exports = {
db: {
host: "localhost",
user: "root",
password: "1234",
database: "farmbot"
},
port: 3000
};

You will have to refactor them properly. You will need only once file to begin with. Why using it twice?
Refactor them in one file instead of listening to them on different ports. Once done, you can show the code to us so that we can fix it further if there's an issue.
Start from index.js and merge app.js with it but a bit carefully. I think doing it by yourself you will learn much from it.

running nodejs and mysql, how can I parse the result in client

var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT * FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
in my c# I have
IRestResponse response = client.Execute(request);
var content = response.Content;
but the content prints "Internal Error" for all err types
EDIT
Also tried:
pool.getConnection((err, conn) => {
if(err) {
var error = new Error("something is wrong");
callback(error);
}
according to this https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-mode-exceptions.html, still getting Internal Error for all error types
Also, I do get 200 OK on good requests, what I am trying to do is to print an explanatory message to the client in case of an error

How to make DBconnection and Node.js Query file separately

I have question. How to connect dbconnection.js and demo_api_select.js I have a problem when declare variable on demo_api_select.js. It doesn't work and have error notification like this:
Error Notification
Please help
dbconnection.js:
var mysql=require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: "test"
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
});
module.exports = con;
demo_api_select.js
var db = require('./dbconnection');
db.connect(function(err) {
if (err) throw err;
//Select all customers and return the result object:
con.query("SELECT * FROM profil" , function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
I want to make those code work as well as this code:
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: "test"
});
con.connect(function(err) {
if (err) throw err;
//Select all customers and return the result object:
con.query("SELECT * FROM profil" , function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});

Try this code.No need to connect twice to database
var db = require('./dbconnection');
db.query("SELECT * FROM profil" , function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});

Why the server not accessing connection variable?

I'm trying to retrieve data from database using Node.js restify framework. The server is running fine but when I visit http://localhost:8081/get I get this error:
{
"code": "InternalError",
"message": "connectionPool is not defined"
}
Here's my code:
server.js
require('./app/core/routes.js');
routes.js
var restify=require('restify');
var fs=require('fs');
var controllers = {};
controllers_path = process.cwd() + '/app/controllers';
fs.readdirSync(controllers_path).forEach(function (file) {
if (file.indexOf('.js') != -1) {
controllers[file.split('.')[0]] = require(controllers_path + '/' + file);
}
});
var server=restify.createServer();
server.get('/get', controllers.article.printHello);
server.listen(8081, function (err) {
if (err)
console.error(err);
else
console.log('App is ready at : ' + 8081);
});
article.js
var something2=require('../core/connection.js');
something2.something();
exports.printHello= function(req, res, next){
connectionPool.getConnection(function (err, connection) {
if (err) {
res.send({
Error: err,
Message: "Can't connect Database."
});
} else {
//queries
connection.query("SELECT * FROM book", function (err, rows, fields) {
res.send({
json: rows
});
});
}
});
};
connection.js
var mysql = require('mysql');
exports.something = function () {
var connectionPool = mysql.createPool({
host: 'localhost',
user: 'root',
password: '',
database: 'books'
});
}

In your connection.js file, export the pool
var mysql = require('mysql');
exports.connectionPool = function() {
return mysql.createPool({
host: 'localhost',
user: 'root',
password: '',
database: 'books'
});
}
Then use it in your article.js file
var conn = require('../core/connection.js');
var pool = conn.connectionPool();
exports.printHello = function(req, res, next){
pool.getConnection(function (err, connection) {
if (err) { ...

You have to return your variable connectionPool in your connection.js's something function.
connection.js
var mysql = require('mysql');
exports.something = function () {
var connectionPool = mysql.createPool({
host: 'localhost',
user: 'root',
password: '',
database: 'books'
});
return connectionPool; // notice here
}
article.js
var something2=require('../core/connection.js');
var connectionPool = something2.something(); //notice here
exports.printHello= function(req, res, next){
connectionPool.getConnection(function (err, connection) {
if (err) {
res.send({
Error: err,
Message: "Can't connect Database."
});
} else {
//queries
connection.query("SELECT * FROM book", function (err, rows, fields) {
res.send({
json: rows
});
});
}
});
};

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