https://i.imgur.com/w5quRwA.jpg
I manually created a database called "shoppingitems" on the mongodb website console. I then created a model called "products" in an Express app and connected to the database. A collection called "products" was added to the "shoppingitems" database like I expected.
I then went to add a document to the "shoppingitems.products" collection, but instead an entirely new database called "test" was created, with a products collection and my submitted document in that 'test.products" collection instead of the "shoppingitems.products" collection like I intended.
Is there something wrong with my code? I make no mention of a "test" database anywhere, so IDK why it was created in the first place.
index.js
//Express
var express = require("express");
const app = express();
app.use(express.json());
//Mongoose
const dotenv = require("dotenv");
dotenv.config();
const mongoose = require("mongoose");
mongoose
.connect(process.env.MONGO_URL, {
useNewUrlParser: true,
useUnifiedTopology: true,
})
.then(() => console.log("db connection succesfull"))
.catch((err) => console.log(err));
//CORS
const cors = require("cors");
app.use(cors());
//Routes
const productRoute = require("./routes/products");
app.use("/", productRoute);
//RUN INDEX.JS
app.listen(5000, () => {
console.log("backend server is running");
});
routes/products.js
var express = require("express");
var router = express.Router();
var Product = require("../models/Products");
/* GET PRODUCTS FOR HOMEPAGE */
router.get("/", async (req, res) => {
try {
productList = await Product.find();
res.json(productList);
} catch (error) {
console.log(error);
}
});
//POST PRODUCTS TO DATABASE
router.post("/", async (request, response) => {
console.log("request.body= ", request.body);
const newProduct = new Product(request.body);
try {
const savedProduct = await newProduct.save();
response.status(201).json(savedProduct);
} catch (err) {
response.status(500).json(err);
}
});
module.exports = router;
models/Products.js
const mongoose = require("mongoose");
const ProductSchema = new mongoose.Schema({
name: { type: String },
price: { type: Number },
description: { type: String },
image: { type: String },
stripeId: { type: String },
});
module.exports = mongoose.model("Product", ProductSchema);
Am I missing something? I don't see anything in the code that would be causing this and creating a "test" database. I've only used Mongo once or twice before though so I'm not exactly an expert. Can anybody here see what I'm doing wrong?
I'll post any additional code or information that you think is necessary to solving this. Just tell me what else you need to see.
test is the default database name used if you don't specify one. I also notice that nowhere in the code is a shoppingsitems database mentioned.
The connection string could contain the database name, but in this code that is taken from an environment variable.
I've been trying to connect my application to my database, but it has not been possible. I've tried this below, and it still did not recognize my models
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = process.env.MONGODB_URL;
// Database Name
const dbName = 'KaydeeAcedemy';
// Use connect method to connect to the server
MongoClient.connect(url, { useNewUrlParser: true, useUnifiedTopology: true }, function(err, client) {
assert.equal(null, err);
console.log("Connected successfully to server");
const db = client.db(dbName);
client.close();
});
I've also tried using this connection string, yet no headway.
const { MongoClient } = require('mongodb');
const uri = process.env.MONGODB_URL;
const client = new MongoClient(uri, { useNewUrlParser: true, useUnifiedTopology: true });
client.connect(err => {
const collection = client.db("test").collection("devices");
// perform actions on the collection object
client.close();
});
when I try to add a new user from my application, i get this error as a result of the database.
Operation `users.findOne()` buffering timed out after 10000ms
the mongodb url looks like this:
MONGODB_URL = mongodb+srv://Kaydeeacademy:**************#cluster0.ehclf.mongodb.net/KaydeeAcademy?retryWrites=true&w=majority
I don't know if I missed something in the connection string or somewhere.
Can you test/compare out some of my code (working)
// have you called in the dot.env file?
require('dotenv').config()
const express = require('express')
const mongoose = require('mongoose')
// don't include the "useNewUrlParser: true, useUnifiedTopology: true" see answer below:
// https://stackoverflow.com/questions/68915722/option-usefindandmodify-is-not-supported
// make sure there are no spaces in the dot.env file
mongoose.connect(process.env.MONGO_URI)
.then(() => console.log("db connected!"))
.catch(err => console.error("db connection failed ", err))
For my discord bot, I was thinking of separating the mongoose connect method and other initialization to a separate JS file. I was able to move everything except for the connect method. I don't know how this could be done.
Try below code
// Declare mongoose as global
global.mongoose = require('mongoose');
// In Separate file
const url = "Your URL";
//BUILD A CONNECTION
mongoose.connect(url).then(() => { console.log('Connected To database :)')})
.catch( err => console.log('error', err));
module.exports.mongoose = mongoose
// Schema File
const users = new mongoose.Schema({
name : String,
}, {
timestamps : true
})
module.exports = mongoose.model('users', users);
// In model Path
const usersModel = require('Schemas/users')
now you can use usersModel to query documents/table
// suppose this filename is, mongoose.db.config.js
const mongoose = require("mongoose");
function mongooseConnectDB(uri) {
mongoose
.connect(uri, {
useNewUrlParser: true,
useUnifiedTopology: true,
useFindAndModify: false,
useCreateIndex: true,
})
.then((result) =>
console.log("Mongoose connected to ", result.connections[0].host)
)
.catch((err) => console.log("error connecting to the database", err));
}
module.exports = mongooseConnectDB;
Now in your app(main.js/index.js/server.js), you can do simply like this
const mongooseConnectDB = require("./mongoose.db.config");
mongooseConnectDB('url_of_your_db');
This question already has answers here:
db.collection is not a function when using MongoClient v3.0
(13 answers)
Closed 3 years ago.
I'm setting up a new app using an Atlas Database with node and all i get is an error saying " MongoError: MongoClient must be connected before calling MongoClient.prototype.db".
const uri = "mongodb+srv://alberto:pass#lel-kicis.mongodb.net/test";
const client = new MongoClient(uri, { useNewUrlParser: true });
client.connect(err => {
const collection = client.db("test").collection("students")
.then(db => console.log('DB conectada'))
.catch(err => console.log(error));
});
If you look at the mongodb connector docs, the syntax for MongoClient is new MongoClient(url, options, callback). The signature for the callback is (err, client) => { //body }.
If you don't pass in the optional callback, you get and instance of MongoClient (which is the case here). The connect method also expects the same callback signature, so your connection should be like:
const instance = new MongoClient(uri, { useNewUrlParser: true });
// notice 'client' in the callback
instance.connect((err, client) => {
if (err) console.log('failed to connect')
else {
console.log('connected')
const collection = client.db("test").collection("students")
...
}
});
mongodb connector also support promise, so you can also do:
// connection is a promise
const connection = instance.connect()
connection.then((err, client) => { // etc })
Using mongoose and mongodb-uri :
Here is the way I initialise the connection :
const mongoose = require('mongoose')
const uriUtil = require('mongodb-uri')
// Create a new connection
mongoose.Promise = global.Promise
// mongoose.set('debug', DEBUG)
const dbURI = uriUtil.formatMongoose(process.env.MONGO_URI)
const options = {
autoIndex: DEBUG,
autoReconnect: true,
useNewUrlParser: true
}
const conn = mongoose.createConnection(dbURI, options)
conn.on('open', () => console.log('DB connection open'))
conn.on('error', err => console.log(`DB connection error : ${err.message}`, err))
conn.on('close', () => console.log('DB connection closed'))
module.exports = conn
Using the connection string provided by mongoDb for driver node.js version 3.0 or later.
You are missing to initiate the mongo client.
const MongoClient = require('mongodb').MongoClient;
const uri = "mongodb+srv://alberto:pass#lel-kicis.mongodb.net/test";
const client = new MongoClient(uri, { useNewUrlParser: true });
client.connect(err => {
const collection = client.db("test").collection("students")
.then(db => console.log('DB conectada'))
.catch(err => console.log(error));
});
Also, Atlas generate the initial connection code block for you. Follow the below steps.
Clck on connect button
Select Connect Your Application from the next window
On the next window, Select NodeJs as driver and select the required version. Also, select Full driver example for full code block
Now copy the code and use it directly.
I'm using the node-mongodb-native driver with MongoDB to write a website.
I have some questions about how to manage connections:
Is it enough using only one MongoDB connection for all requests? Are there any performance issues? If not, can I setup a global connection to use in the whole application?
If not, is it good if I open a new connection when request arrives, and close it when handled the request? Is it expensive to open and close a connection?
Should I use a global connection pool? I hear the driver has a native connection pool. Is it a good choice?
If I use a connection pool, how many connections should be used?
Are there other things I should notice?
The primary committer to node-mongodb-native says:
You open do MongoClient.connect once when your app boots up and reuse
the db object. It's not a singleton connection pool each .connect
creates a new connection pool.
So, to answer your question directly, reuse the db object that results from MongoClient.connect(). This gives you pooling, and will provide a noticeable speed increase as compared with opening/closing connections on each db action.
Open a new connection when the Node.js application starts, and reuse the existing db connection object:
/server.js
import express from 'express';
import Promise from 'bluebird';
import logger from 'winston';
import { MongoClient } from 'mongodb';
import config from './config';
import usersRestApi from './api/users';
const app = express();
app.use('/api/users', usersRestApi);
app.get('/', (req, res) => {
res.send('Hello World');
});
// Create a MongoDB connection pool and start the application
// after the database connection is ready
MongoClient.connect(config.database.url, { promiseLibrary: Promise }, (err, db) => {
if (err) {
logger.warn(`Failed to connect to the database. ${err.stack}`);
}
app.locals.db = db;
app.listen(config.port, () => {
logger.info(`Node.js app is listening at http://localhost:${config.port}`);
});
});
/api/users.js
import { Router } from 'express';
import { ObjectID } from 'mongodb';
const router = new Router();
router.get('/:id', async (req, res, next) => {
try {
const db = req.app.locals.db;
const id = new ObjectID(req.params.id);
const user = await db.collection('user').findOne({ _id: id }, {
email: 1,
firstName: 1,
lastName: 1
});
if (user) {
user.id = req.params.id;
res.send(user);
} else {
res.sendStatus(404);
}
} catch (err) {
next(err);
}
});
export default router;
Source: How to Open Database Connections in a Node.js/Express App
Here is some code that will manage your MongoDB connections.
var MongoClient = require('mongodb').MongoClient;
var url = require("../config.json")["MongoDBURL"]
var option = {
db:{
numberOfRetries : 5
},
server: {
auto_reconnect: true,
poolSize : 40,
socketOptions: {
connectTimeoutMS: 500
}
},
replSet: {},
mongos: {}
};
function MongoPool(){}
var p_db;
function initPool(cb){
MongoClient.connect(url, option, function(err, db) {
if (err) throw err;
p_db = db;
if(cb && typeof(cb) == 'function')
cb(p_db);
});
return MongoPool;
}
MongoPool.initPool = initPool;
function getInstance(cb){
if(!p_db){
initPool(cb)
}
else{
if(cb && typeof(cb) == 'function')
cb(p_db);
}
}
MongoPool.getInstance = getInstance;
module.exports = MongoPool;
When you start the server, call initPool
require("mongo-pool").initPool();
Then in any other module you can do the following:
var MongoPool = require("mongo-pool");
MongoPool.getInstance(function (db){
// Query your MongoDB database.
});
This is based on MongoDB documentation. Take a look at it.
Manage mongo connection pools in a single self contained module. This approach provides two benefits. Firstly it keeps your code modular and easier to test. Secondly your not forced to mix your database connection up in your request object which is NOT the place for a database connection object. (Given the nature of JavaScript I would consider it highly dangerous to mix in anything to an object constructed by library code). So with that you only need to Consider a module that exports two methods. connect = () => Promise and get = () => dbConnectionObject.
With such a module you can firstly connect to the database
// runs in boot.js or what ever file your application starts with
const db = require('./myAwesomeDbModule');
db.connect()
.then(() => console.log('database connected'))
.then(() => bootMyApplication())
.catch((e) => {
console.error(e);
// Always hard exit on a database connection error
process.exit(1);
});
When in flight your app can simply call get() when it needs a DB connection.
const db = require('./myAwesomeDbModule');
db.get().find(...)... // I have excluded code here to keep the example simple
If you set up your db module in the same way as the following not only will you have a way to ensure that your application will not boot unless you have a database connection you also have a global way of accessing your database connection pool that will error if you have not got a connection.
// myAwesomeDbModule.js
let connection = null;
module.exports.connect = () => new Promise((resolve, reject) => {
MongoClient.connect(url, option, function(err, db) {
if (err) { reject(err); return; };
resolve(db);
connection = db;
});
});
module.exports.get = () => {
if(!connection) {
throw new Error('Call connect first!');
}
return connection;
}
If you have Express.js, you can use express-mongo-db for caching and sharing the MongoDB connection between requests without a pool (since the accepted answer says it is the right way to share the connection).
If not - you can look at its source code and use it in another framework.
You should create a connection as service then reuse it when need.
// db.service.js
import { MongoClient } from "mongodb";
import database from "../config/database";
const dbService = {
db: undefined,
connect: callback => {
MongoClient.connect(database.uri, function(err, data) {
if (err) {
MongoClient.close();
callback(err);
}
dbService.db = data;
console.log("Connected to database");
callback(null);
});
}
};
export default dbService;
my App.js sample
// App Start
dbService.connect(err => {
if (err) {
console.log("Error: ", err);
process.exit(1);
}
server.listen(config.port, () => {
console.log(`Api runnning at ${config.port}`);
});
});
and use it wherever you want with
import dbService from "db.service.js"
const db = dbService.db
I have been using generic-pool with redis connections in my app - I highly recommend it. Its generic and I definitely know it works with mysql so I don't think you'll have any problems with it and mongo
https://github.com/coopernurse/node-pool
I have implemented below code in my project to implement connection pooling in my code so it will create a minimum connection in my project and reuse available connection
/* Mongo.js*/
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/yourdatabasename";
var assert = require('assert');
var connection=[];
// Create the database connection
establishConnection = function(callback){
MongoClient.connect(url, { poolSize: 10 },function(err, db) {
assert.equal(null, err);
connection = db
if(typeof callback === 'function' && callback())
callback(connection)
}
)
}
function getconnection(){
return connection
}
module.exports = {
establishConnection:establishConnection,
getconnection:getconnection
}
/*app.js*/
// establish one connection with all other routes will use.
var db = require('./routes/mongo')
db.establishConnection();
//you can also call with callback if you wanna create any collection at starting
/*
db.establishConnection(function(conn){
conn.createCollection("collectionName", function(err, res) {
if (err) throw err;
console.log("Collection created!");
});
};
*/
// anyother route.js
var db = require('./mongo')
router.get('/', function(req, res, next) {
var connection = db.getconnection()
res.send("Hello");
});
If using express there is another more straightforward method, which is to utilise Express's built in feature to share data between routes and modules within your app. There is an object called app.locals. We can attach properties to it and access it from inside our routes. To use it, instantiate your mongo connection in your app.js file.
var app = express();
MongoClient.connect('mongodb://localhost:27017/')
.then(client =>{
const db = client.db('your-db');
const collection = db.collection('your-collection');
app.locals.collection = collection;
});
// view engine setup
app.set('views', path.join(__dirname, 'views'));
This database connection, or indeed any other data you wish to share around the modules of you app can now be accessed within your routes with req.app.locals as below without the need for creating and requiring additional modules.
app.get('/', (req, res) => {
const collection = req.app.locals.collection;
collection.find({}).toArray()
.then(response => res.status(200).json(response))
.catch(error => console.error(error));
});
This method ensures that you have a database connection open for the duration of your app unless you choose to close it at any time. It's easily accessible with req.app.locals.your-collection and doesn't require creation of any additional modules.
Best approach to implement connection pooling is you should create one global array variable which hold db name with connection object returned by MongoClient and then reuse that connection whenever you need to contact Database.
In your Server.js define var global.dbconnections = [];
Create a Service naming connectionService.js. It will have 2 methods getConnection and createConnection.
So when user will call getConnection(), it will find detail in global connection variable and return connection details if already exists else it will call createConnection() and return connection Details.
Call this service using <db_name> and it will return connection object if it already have else it will create new connection and return it to you.
Hope it helps :)
Here is the connectionService.js code:
var mongo = require('mongoskin');
var mongodb = require('mongodb');
var Q = require('q');
var service = {};
service.getConnection = getConnection ;
module.exports = service;
function getConnection(appDB){
var deferred = Q.defer();
var connectionDetails=global.dbconnections.find(item=>item.appDB==appDB)
if(connectionDetails){deferred.resolve(connectionDetails.connection);
}else{createConnection(appDB).then(function(connectionDetails){
deferred.resolve(connectionDetails);})
}
return deferred.promise;
}
function createConnection(appDB){
var deferred = Q.defer();
mongodb.MongoClient.connect(connectionServer + appDB, (err,database)=>
{
if(err) deferred.reject(err.name + ': ' + err.message);
global.dbconnections.push({appDB: appDB, connection: database});
deferred.resolve(database);
})
return deferred.promise;
}
In case anyone wants something that works in 2021 with Typescript, here's what I'm using:
import { MongoClient, Collection } from "mongodb";
const FILE_DB_HOST = process.env.FILE_DB_HOST as string;
const FILE_DB_DATABASE = process.env.FILE_DB_DATABASE as string;
const FILES_COLLECTION = process.env.FILES_COLLECTION as string;
if (!FILE_DB_HOST || !FILE_DB_DATABASE || !FILES_COLLECTION) {
throw "Missing FILE_DB_HOST, FILE_DB_DATABASE, or FILES_COLLECTION environment variables.";
}
const client = new MongoClient(FILE_DB_HOST, {
useNewUrlParser: true,
useUnifiedTopology: true,
});
class Mongoose {
static FilesCollection: Collection;
static async init() {
const connection = await client.connect();
const FileDB = connection.db(FILE_DB_DATABASE);
Mongoose.FilesCollection = FileDB.collection(FILES_COLLECTION);
}
}
Mongoose.init();
export default Mongoose;
I believe if a request occurs too soon (before Mongo.init() has time to finish), an error will be thrown, since Mongoose.FilesCollection will be undefined.
import { Request, Response, NextFunction } from "express";
import Mongoose from "../../mongoose";
export default async function GetFile(req: Request, res: Response, next: NextFunction) {
const files = Mongoose.FilesCollection;
const file = await files.findOne({ fileName: "hello" });
res.send(file);
}
For example, if you call files.findOne({ ... }) and Mongoose.FilesCollection is undefined, then you will get an error.
npm i express mongoose
mongodb.js
const express = require('express');
const mongoose =require('mongoose')
const app = express();
mongoose.set('strictQuery', true);
mongoose.connect('mongodb://localhost:27017/db_name', {
useNewUrlParser: true,
useUnifiedTopology: true
})
.then(() => console.log('MongoDB Connected...'))
.catch((err) => console.log(err))
app.listen(3000,()=>{ console.log("Started on port 3000 !!!") })
node mongodb.js
Using below method you can easily manage as many as possible connection
var mongoose = require('mongoose');
//Set up default mongoose connection
const bankDB = ()=>{
return mongoose.createConnection('mongodb+srv://<username>:<passwprd>#mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
}
bankDB().then(()=>console.log('Connected to mongoDB-Atlas bankApp...'))
.catch((err)=>console.error('Could not connected to mongoDB',err));
//Set up second mongoose connection
const myDB = ()=>{
return mongoose.createConnection('mongodb+srv://<username>:<password>#mydemo.jk4nr.mongodb.net/<database>?retryWrites=true&w=majority',options);
}
myDB().then(()=>console.log('Connected to mongoDB-Atlas connection 2...'))
.catch((err)=>console.error('Could not connected to mongoDB',err));
module.exports = { bankDB(), myDB() };