Develop Reference

SQL SELECT FROM with multiple variables

I would like to make a SELECT FROM request, and instead of having the name of the column ( which is Alan), I would like to replace it by a variable ( which is the variable named pseudo), I know it can be done in php, but i am trying to do it in javascript using Node.js.
I have tried to replace the name og the column but the result in the console is wrong.
there are no error messages, but the data shown in the console is empty, it shows just an empty parenthesis.
var pseudo = "Alan";
var onlinepeers = "Sarah";
var mysql = require('mysql');
let connection = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: "espace_membre"
});
connection.connect(function(err) {
if (err) throw err;
connection.query("SELECT ALan FROM matches WHERE Alan = '" + onlinepeers + "'", function(err, result) {
if (err) throw err;
console.log(result);
});
});

You can try something Like this,Using template literals
var pseudo = "Alan";
var onlinepeers = "Sarah";
var mysql = require('mysql');
let connection = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: "espace_membre"
});
connection.connect(function(err) {
if (err) throw err;
connection.query(`SELECT Alan FROM matches WHERE ${pseudo}=${onlinepeers}`, function (err, result) {
if (err) throw err;
console.log(result);
});
});
Better Use Parametriezed Query
let sql=`SELECT Alan FROM matches WHERE ${pseudo} =?`
connection.connect(function(err) {
if (err) throw err;
connection.query(sql,[onlinepeers], function (err, result) {
if (err) throw err;
console.log(result);
});
});

First create a queryString as follows:
let queryString = "SELECT " + pseudo + " FROM matches WHERE " + pseudo + " = .....
then:
Use the variable queryString in your connection.query(queryString)

Canno add values to database by javascript

I am getting an error on node.js, and I cannot identify why. Can anybody help me? If I add only 1 data from the array it gets added to the database. However, when I add other inputs, it displays an error in node.js and doesn't get saved in my database.
var express = require('express');
var app = express();
app.get('/register/*', handleGetRequest); //how do I pass usrName here?
app.use(express.static('public'));
app.listen(5000);
function handleGetRequest(request, response){
var pathArray = request.url.split("/");
var pathEnd = pathArray[pathArray.length - 1];
if(pathEnd === 'register'){
response.send("{working}");
//console.log(request.body.usrName);
}
else
var registerArray = pathEnd.split("&");
response.send(JSON.stringify(registerArray));
saveToDb(registerArray);
// response.send("{error: 'Path not recognized'}");
}
function saveToDb(registerArray){
for (var i = 0; i < registerArray.length; i++) {
console.log(registerArray[i]);
}
var mysql = require('mysql');
var con = mysql.createConnection({
host: 'localhost',
user: 'root',
password: '',
database: 'customer',
port: 6000
});
con.connect();
addData();
function addData(){
var query = con.query(
"INSERT INTO cust (id,LastName,FirstName) VALUES
('001,"+registerArray[0]+"," +registerArray[1]+"');",function(err, result,
fields){
if (err) throw err;
console.log('results' , result);
}
);
}
//Close the connection
con.end();
}

You are missing single quotes in your SQL statement that cause the problem. The code should look like this:
function addData(){
var query = con.query(
"INSERT INTO cust (id,LastName,FirstName) VALUES
('001','"+registerArray[0]+"','" +registerArray[1]+"');",
function(err, result, fields) {
if (err) throw err;
console.log('results' , result);
}
);
}

How to use another MongoDB database using Node.js [duplicate]

How do I connect to mongodb with node.js?
I have the node-mongodb-native driver.
There's apparently 0 documentation.
Is it something like this?
var mongo = require('mongodb/lib/mongodb');
var Db= new mongo.Db( dbname, new mongo.Server( 'mongolab.com', 27017, {}), {});
Where do I put the username and the password?
Also how do I insert something?
Thanks.

Per the source:
After connecting:
Db.authenticate(user, password, function(err, res) {
// callback
});

Everyone should use this source link:
http://mongodb.github.com/node-mongodb-native/contents.html
Answer to the question:
var Db = require('mongodb').Db,
MongoClient = require('mongodb').MongoClient,
Server = require('mongodb').Server,
ReplSetServers = require('mongodb').ReplSetServers,
ObjectID = require('mongodb').ObjectID,
Binary = require('mongodb').Binary,
GridStore = require('mongodb').GridStore,
Code = require('mongodb').Code,
BSON = require('mongodb').pure().BSON,
assert = require('assert');
var db = new Db('integration_tests', new Server("127.0.0.1", 27017,
{auto_reconnect: false, poolSize: 4}), {w:0, native_parser: false});
// Establish connection to db
db.open(function(err, db) {
assert.equal(null, err);
// Add a user to the database
db.addUser('user', 'name', function(err, result) {
assert.equal(null, err);
// Authenticate
db.authenticate('user', 'name', function(err, result) {
assert.equal(true, result);
db.close();
});
});
});

var mongo = require('mongodb');
var MongoClient = mongo.MongoClient;
MongoClient.connect('mongodb://'+DATABASEUSERNAME+':'+DATABASEPASSWORD+'#'+DATABASEHOST+':'DATABASEPORT+'/'+DATABASENAME,function(err, db){
if(err)
console.log(err);
else
{
console.log('Mongo Conn....');
}
});
//for local server
//in local server DBPASSWOAD and DBusername not required
MongoClient.connect('mongodb://'+DATABASEHOST+':'+DATABASEPORT+'/'+DATABASENAME,function(err, db){
if(err)
console.log(err);
else
{
console.log('Mongo Conn....');
}
});

I find using a Mongo url handy. I store the URL in an environment variable and use that to configure servers whilst the development version uses a default url with no password.
The URL has the form:
export MONGODB_DATABASE_URL=mongodb://USERNAME:PASSWORD#DBHOST:DBPORT/DBNAME
Code to connect this way:
var DATABASE_URL = process.env.MONGODB_DATABASE_URL || mongodb.DEFAULT_URL;
mongo_connect(DATABASE_URL, mongodb_server_options,
function(err, db) {
if(db && !err) {
console.log("connected to mongodb" + " " + lobby_db);
}
else if(err) {
console.log("NOT connected to mongodb " + err + " " + lobby_db);
}
});

My version:
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://user:pass#dhost:port/baseName', function(err, db) {
if (err) {
console.error(err);
}
var collection = db.collection('collectionName');
collection.find().toArray(function(err, docs) {
console.log(docs);
});
});

I recommend mongoskin I just created.
var mongo = require('mongoskin');
var db = mongo.db('admin:pass#localhost/mydb?auto_reconnnect');
db.collection('mycollection').find().toArray(function(err, items){
// do something with items
});
Is mongoskin sync? Nop, it is async.

Here is new may to authenticate from "admin" and then switch to your desired DB for further operations:
var MongoClient = require('mongodb').MongoClient;
var Db = require('mongodb').Db, Server = require('mongodb').Server ,
assert = require('assert');
var user = 'user';
var password = 'password';
MongoClient.connect('mongodb://'+user+':'+password+'#localhost:27017/opsdb',{native_parser:true, authSource:'admin'}, function(err,db){
if(err){
console.log("Auth Failed");
return;
}
console.log("Connected");
db.collection("cols").find({loc:{ $eq: null } }, function(err, docs) {
docs.each(function(err, doc) {
if(doc) {
console.log(doc['_id']);
}
});
});
db.close();
});

This worked for me:
Db.admin().authenticate(user, password, function() {} );

You can do it like this
var db = require('mongo-lite').connect('mongodb://localhost/test')
more details ...

if you continue to have problems with the native driver, you can also check out sleepy mongoose. It's a python REST server that you can simply access with node request to get to your Mongo instance.
http://www.snailinaturtleneck.com/blog/2010/02/22/sleepy-mongoose-a-mongodb-rest-interface/

With the link provided by #mattdlockyer as reference, this worked for me:
var mongo = require('mongodb');
var server = new mongo.Server(host, port, options);
db = new mongo.Db(mydb, server, {fsync:true});
db.open(function(err, db) {
if(!err) {
console.log("Connected to database");
db.authenticate(user, password, function(err, res) {
if(!err) {
console.log("Authenticated");
} else {
console.log("Error in authentication.");
console.log(err);
}
});
} else {
console.log("Error in open().");
console.log(err);
};
});
exports.testMongo = function(req, res){
db.collection( mycollection, function(err, collection) {
collection.find().toArray(function(err, items) {
res.send(items);
});
});
};

Slight typo with Chris' answer.
Db.authenticate(user, password, function({ // callback }));
should be
Db.authenticate(user, password, function(){ // callback } );
Also depending on your mongodb configuration, you may need to connect to admin and auth there first before going to a different database. This will be the case if you don't add a user to the database you're trying to access. Then you can auth via admin and then switch db and then read or write at will.

const { MongoClient } = require('mongodb');
// or as an es module:
// import { MongoClient } from 'mongodb'
// Connection URL
const url = 'mongodb://localhost:27017';
const client = new MongoClient(url);
// Database Name
const dbName = 'myProject';
async function main() {
// Use connect method to connect to the server
await client.connect();
console.log('Connected successfully to server');
const db = client.db(dbName);
const collection = db.collection('documents');
// the following code examples can be pasted here...
return 'done.';
}
main()
//what to do next
.then(console.log)
//if there is an error
.catch(console.error)
// what to do in the end(function result won't matter here, it will execute always).
.finally(() => client.close());
you can find more in the documentation here: https://mongodb.github.io/node-mongodb-native/4.1/

I'm using Mongoose to connect to mongodb.
Install mongoose npm using following command
npm install mongoose
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/database_name', function(err){
if(err){
console.log('database not connected');
}
});
var Schema = mongoose.Schema;
var userschema = new Schema ({});
var user = mongoose.model('collection_name', userschema);
we can use the queries like this
user.find({},function(err,data){
if(err){
console.log(err);
}
console.log(data);
});

Passing Object with module exports

I am still new to nodejs and Javascript, I am sorry if my question appear to be very simple but I am struggling a lot and I can't seem to find an answer on the net.
What I want to do is basically calling a script (sqlRequest.js) and send an integer while calling it. This script will send an sql request to my database and will return the result (an object) to the original file.
Here are the codes:
router.post('/request', function(req, res, next){
var id = req.body.id;
var essai = require('./sqlRequest.js');
console.log("INDEX: "+essai.sendSQL(id)); });
And now the sqlRequest.js code:
exports.sendSQL = function(id) {
var mysql= require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'bcombes',
password : 'bertrand1994',
database : 'totalkpi'
});
connection.connect();
var sql ="SELECT * FROM tra_ticket where id=?";
var insert=[id];
sql=mysql.format(sql, insert);
connection.query(sql, function(err, rows, fields) {
if (err) {
console.log('Error while performing Query.');
connection.end();
}
else {
connection.end();
console.log(rows);
return rows;
}
});};
On the console I can see that the console.log("INDEX: "+essai.sendSQL(id)); appears to be undefined and is displayed before the console.log(rows).
Is it possible that the server does not wait for the function to finish and display the variable anyway ?
Anyway thank you for taking the time to help.

Your logic to pass a variable between files is fine. The reason your seeing essai.sendSQL(id) return undefined is because connection.query(...) is called asynchronously and, as you've mentioned in your question, the console.log fires before the DB query completes.
To fix that issue you just need to refactor your code slightly:
var essai = require('./sqlRequest.js');
router.post('/request', function(req, res, next){
var id = req.body.id;
// send callback to sendSQL
essai.sendSQL(id, function(index) {
// this will only fire once the callback has been called
console.log("INDEX: " + index)
})
});
And then in sqlRequest.js:
exports.sendSQL = function (id, cb) {
var mysql = require('mysql');
var connection = mysql.createConnection({
host: 'localhost',
user: 'bcombes',
password: 'bertrand1994',
database: 'totalkpi'
});
connection.connect();
var sql = "SELECT * FROM tra_ticket where id=?";
var insert = [id];
sql = mysql.format(sql, insert);
connection.query(sql, function (err, rows, fields) {
if (err) {
console.log('Error while performing Query.');
connection.end();
}
else {
connection.end();
console.log(rows);
// call the callback
cb(rows);
}
});
};

child_process.fork - process.send does not return message

I am running this script with node child_process.fork api.
That is my express application script, from where I start my application:
/**
* Module dependencies.
*/
var express = require('express')
, routes = require('./routes')
, http = require('http')
, path = require('path');
var app = express();
//database connection
var connection = require('express-myconnection');
var mysql = require('mysql');
//all environments
app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(express.static(path.join(__dirname, 'public')));
//development only
if ('development' == app.get('env')) {
app.use(express.errorHandler());
}
app.use(
connection(mysql,{
host: 'localhost',
user: 'root',
password : '',
port : 3306, //port mysql
database:'test-db'
},'pool')
);
//routes
//app.get('/', routes.index);
app.get('/', routes.list);
app.use(app.router);
//run script
var cp = require('child_process');
var child = cp.fork('dataGrabber/pusherMysql');
child.on('message', function(m) {
// Receive results from child process
console.log('received: ' + m);
});
http.createServer(app).listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port') + ' http://localhost:' + app.get('port'));
});
That`s the part where I run my script:
//run script
var cp = require('child_process');
var child = cp.fork('dataGrabber/pusherAPI');
child.on('message', function(m) {
// Receive results from child process
console.log('received: ' + m);
});
As you can see I load my script and want to receive a message from the child.
That is my pusherAPI.js script:
var mysql = require('mysql');
var Pusher = require('pusher-client');
/**
* connect with mysql db
*/
var connection = mysql.createConnection({
host : 'localhost',
user : 'root',
database : 'test-db',
port : '3306',
password : ''
});
connection.connect(function(err) {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
console.log('connected as id ' + connection.threadId);
});
//connect with the server
var API_KEY = 'cb65d0a7a72cd94adf1f';
var pusher = new Pusher(API_KEY, {
encrypted: true
});
var channel = pusher.subscribe("ticker.160");
channel.bind("message", function(data) {
console.log(data);
this.data = data;
/**
* save data to db
*/
var trade = {
timestamp : data.trade.timestamp,
price : data.trade.topbuy.price,
};
var query = connection.query('INSERT INTO trades SET ?', trade, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
//push message back to the app.js
process.on('message', function(m) {
// Pass results back to parent process
m = "insert happened";
process.send(m);
});
connection.commit(function(err) {
if (err) {
connection.rollback(function() {
throw err;
});
}
});
});
console.log(query.sql);
});
I want to send a message back to my app.js, whenever an insertion happened to my sql db
My script starts and runs my queries. However, process.send(m); does not send anything back.
Any recommendations what I am doing wrong?
I appreciate your answer!
Update
When changing my pusherAPI.js to, I get nothing back in the console.
var channel = pusher.subscribe("ticker.160");
process.on('insert_message', function(m) {
channel.bind("message", function(data) {
console.log(data);
this.data = data;
/**
* save data to db
*/
var trade = {
timestamp : data.trade.timestamp,
price : data.trade.topbuy.price,
};
var query = connection.query('INSERT INTO trades SET ?', trade, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
//push message back to the app.js
// Pass results back to parent process
m = "insert happened";
process.send(m);
connection.commit(function(err) {
if (err) {
connection.rollback(function() {
throw err;
});
}
});
});
console.log(query.sql);
});
});
In my app.js I changed my code like that:
//run script
var cp = require('child_process');
var child = cp.fork('dataGrabber/pusherAPI');
child.on('insert_message', function(m) {
// Receive results from child process
console.log('received: ' + m);
});

Move your process.send(m); outside of the message event handler. Otherwise you're adding a new message event handler for every query and those event handlers only fire when the parent process sends it a message. Example:
var channel = pusher.subscribe("ticker.160");
channel.bind("message", function(data) {
this.data = data;
/**
* save data to db
*/
var trade = {
timestamp : data.trade.timestamp,
price : data.trade.topbuy.price,
};
var query = connection.query('INSERT INTO trades SET ?',
trade,
function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
return;
}
//push message back to the app.js
m = "insert happened";
process.send(m);
connection.commit(function(err) {
if (err) {
connection.rollback(function() {
throw err;
});
}
});
});
});