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How To Correctly Close My Mongo Connection

I'm playing around with learning javascript/node.js for UI and API testing, so I'm busy creating an API that interacts with a mongo DB.
I've written this small js script to populate my db with two data sets.
my script as it stands works perfectly, but I've noticed in the mongo logs I need to close the connection once I'm done, but I'm struggling on finding a good example of how to do this or struggling to use existing examples to fit my script.
#! /usr/bin/node
//Require mongodb drivers
var mongodb = require("mongodb");
//Call test data to populate db
let movieList = require("./data/MovieList");
let actorList = require("./data/ActorList");
//Create MongoObj
var MongoClient = mongodb.MongoClient;
var url = "mongodb://localhost:27017";
const dbName = "MovieDatabase";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
if (err) {
console.log(`Error - unable to connect to mongodb ${err}`);
process.exit(1);
} else {
console.log(`Connection Successful`);
}
var dbo = db.db(dbName);
if (movieList.getAllMovies !== null) {
createAndPopulateCollections(dbo, 'movies', movieList.getAllMovies)
}
if (actorList.getAllActors !== null){
createAndPopulateCollections(dbo, 'actors', actorList.getAllActors)
}
//db.close();
})
function createAndPopulateCollections(dbo, collectionName, collectionObject) {
dbo.createCollection(collectionName);
dbo
.collection(collectionName)
.insertMany(collectionObject, function(err, result) {
if (err) {
console.log(`ERROR: ${err}`);
process.exit(1);
} else {
console.log(`Success: ${result.insertedCount}`);
process.exit(0);
}
});
}
I'm aware there is probably loads of issues with the above script#!

if you need close your collection you have just write this line in the end of your function
dbo.close();

Organize MongoDB request on Node.JS

I'm actually creating a chat like Discord with servers and channels using Node.JS, MongoDB and Mongoose.
Actually, my structure is this one:
https://github.com/copostic/My-Simple-Chat/tree/master/models
But to get the conversations, I have to make so much nested functions and I would like to know if there was a better way to organize my code..
Here's the code with the nested functions, I'm trying to get the message list of each channel of each server:
"use strict"
const Server = require('../models/server'),
Channel = require('../models/channel'),
Message = require('../models/message'),
User = require('../models/user');
exports.getChannels = function (req, res, next) {
// Only return one message from each conversation to display as snippet
Server.find({members: req.session._id})
.select('_id')
.exec(function (err, servers) {
if (err) {
res.send({ error: err });
return next(err);
}
servers.forEach(function (server) {
Channel.find({ serverId: server })
.exec(function (err, channels) {
// Set up empty array to hold conversations + most recent message
let fullConversations = [];
channels.forEach(function (channel) {
Message.find({
'channelId': channel._id
})
.sort('creationDate')
.limit(1)
.populate({
path: "author",
select: "profile.firstName profile.lastName"
});
.exec(function (err, message) {
if (err) {
res.send({
error: err
});
return next(err);
}
fullConversations.push(message);
if (fullConversations.length === conversations.length) {
return res.status(200).json({
conversations: fullConversations
});
}
});
});
});
});
});
};
Thanks a lot

How to call mongodb collection getall by node.js?

I wanna take the whole list of notifies from mongo db but it returns empty([]) array also I know that i need callback or shorter way of it . Do you have any idea for collecting any data from mongodb by node.js? If I call this /Notifies method (http://127.0.0.1:5000/Notifies)
var MongoClient = require('mongodb').MongoClient;
var express = require("express");
var app = express();
format = require('util').format;
MongoClient.connect('mongodb://127.0.0.1:27017/Test', function (err, db) {
if (err) {
throw err;
} else {
console.log("successfully connected to the database");
}
db.close();
});
app.get('/Notifies', function (req, res) {
// BAD! Creates a new connection pool for every request
console.log('connected');
MongoClient.connect('mongodb://127.0.0.1:27017/Test', function (err, db) {
if (err) throw err;
var coll = db.collection('Notifies');
var arr = [];
coll.find({}, function (err, docs) {
docs.each(function (err, doc) {
if (doc) {
console.log(doc);
arr.push(doc);
} else {
res.end();
}
});
});
return res.json(arr);
});
});
var port = Number(process.env.PORT || 5000);
app.listen(port, function () {
console.log("Listening on " + port);
})

Don't use for docs.each instead of this use .toArray so it will return directly a array and then use Json.stringify to convert it into json string array
MongoClient.connect('mongodb://127.0.0.1:27017/Test', function (err, db) {
if (err) throw err;
var coll = db.collection('Notifies');
coll.find({}).toArray(function (err, result) {
if (err) {
res.send(err);
} else {
res.send(JSON.stringify(result));
}
})
});

The problem is you are returning the empty array from within the function, before the actual DB operation occurs. You need to move the line return res.json(arr);
into the find function:
app.get('/Notifies', function (req, res) {
// BAD! Creates a new connection pool for every request
console.log('connected');
MongoClient.connect('mongodb://127.0.0.1:27017/Test', function (err, db) {
if (err) throw err;
var coll = db.collection('Notifies');
var arr = [];
coll.find({}, function (err, docs) {
console.log(docs);
docs.each(function (err, doc) {
if (doc) {
console.log(doc);
arr.push(doc);
} else {
res.end();
}
});
return res.json(arr);
});
});
});
Also, for future use, do not reuse variable names in nested functions (you have 3 functions that use the variable err).

nodejs mongodb not deleteing based on id

Can you please help me with this code. This code is not deleting the value from MongoDB, while I am running this url : http://localhost:3000/delete/57c6713455a6b92e105c5250.
I am getting this response: {"lastErrorObject":{"n":0},"value":null,"ok":1}, but not deleting .
app.get('/delete/:id', (req, res) => {
var uid = req.params.id;
db.collection('quotes').findOneAndDelete({'_id': uid}, (err, result) => {
if (err) return res.send(500, err);
res.send(result);
});
});

In MongoDB you query a document id(_id) by using the ObjectId constructor and not the ObjectId's string. Thus the query needs to be: { '_id': ObjectId(uid) }.
Example
var mongoClient = require('mongodb').MongoClient;
//Include ObjectId
var ObjectId = require('mongodb').ObjectID;
mongoClient.connect("Your connection string", function(err, db) {
var query = {
_id: ObjectId("id_string") // Important to notice
};
var collection = db.collection('your collection');
collection.find(query, function(err, docs) {
console.log(err, docs);
});
});
Suggestion
//Include ObjectId
var ObjectId = require('mongodb').ObjectID;
app.get('/delete/:id', (req, res) => {
var uid = req.params.id;
//Add object id to query object
db.collection('quotes').findOneAndDelete({'_id': ObjectId(uid)}, (err, result) => {
if (err) return res.send(500, err);
res.send(result);
});
});

Yes. thank you i figured where i did wrong. see below correct answer.
var ObjectId = require('mongodb').ObjectID;
app.get('/delete/:id', (req, res) => {
var uid = req.params.id;
db.collection('quotes').findOneAndDelete({'_id': ObjectId(uid) }, (err, result) => {
if (err) return res.send(500, err);
res.send(result);
});
});

This response means, your query is executing properly "OK":1, but the find query is unable to find any doc to delete it.
So before using "findOneAndDelete" use only "findOne" and log the response to check weather you that doc or not.

Node access multiple databases

I want to connect to different databases on server side so I can perform queries that include those two databases using node.
I have a config.js like this:
module.exports = {
database: {
user: 'brunojs',
password: 'bdpf5',
connectString: 'localhost:1521/orcl'
},
jwtSecretKey: "jmvhDdDBMvqb=M#6h&QVA7x"
};
This saves my info for accessing the first database.
Then I have one list.js file which performs the query:
var oracledb = require('oracledb');
var jwt = require('jsonwebtoken');
var config = require(__dirname + '../../config.js');
function get(req, res, next) {
oracledb.getConnection(
config.database,
function(err, connection){
if (err) {
return next(err);
}
connection.execute(
'select num_sequencial, notes, des_especialidade, dt_diag ' +
'from organite_repository ',
{},//no binds
{
outFormat: oracledb.OBJECT
},
function(err, results){
if (err) {
connection.release(function(err) {
if (err) {
console.error(err.message);
}
});
return next(err);
}
res.status(200).json(results.rows);
connection.release(function(err) {
if (err) {
console.error(err.message);
}
});
}
);
}
);
}
module.exports.get = get;
Everything works fine.
The thing is, right now, I want to perform queries using another database. How can I do that?

the right solution is to use pool https://github.com/oracle/node-oracledb/blob/master/doc/api.md#createpool
Creating massive pool:
module.exports = {
database: [{user: 'brunojs',
password: 'bdpf5',
connectString: 'localhost:1521/orcl',
poolAlias:'database1'
},
{user: 'brunojs',
password: 'bdpf5',
connectString: 'localhost2:1521/orcl',
poolAlias:'database2'
}],
jwtSecretKey: "jmvhDdDBMvqb=M#6h&QVA7x"
};
during initialization web-server, initialize the pools
const dbConfig = require('../config/database.js');
async function initialize() {
dbConfig.database.forEach(async function(item) {
const pool = await oracledb.createPool(item);
});
}
Then you can use the created pools when calling the connection procedure:
conn = await oracledb.getConnection('database1');
const execresult = await conn.execute(context.execsql, execbinds, context.opts);

First, add a second credentials object in your config.js
module.exports = {
database: {
user: 'brunojs',
password: 'bdpf5',
connectString: 'localhost:1521/orcl'
},
database2: {
user: 'user2',
password: 'password',
connectString: 'someotherhost:1521/orcl'
},
jwtSecretKey: "jmvhDdDBMvqb=M#6h&QVA7x"
};
then use one or other here:
oracledb.getConnection(
config.database, // you could change this line to config.database2
function(err, connection){
if (err) { ...
If you want to query one database, then another, you'd need to keep references to both connection objects (error checking omitted for brevity):
oracledb.GetConnection(
config.database,
function(err, connection1) {
oracledb.GetConnection(
config.database2,
function(err, connection2) {
// in this function you can use either connection object
connection1.execute(...);
connection2.execute(...);
}
});

This is slightly out of scope for your question, but you could also take a look at Waterline. It supports setting up multiple databases and then tying models to them, so that knowing where certain data models are stored is abstracted away.

you can always use links on the DB side, so your java code does not have to connect to another DB, for example:
select num_sequencial, notes, des_especialidade, dt_diag
from organite_repository#linkA
UNION
select num_sequencial, notes, des_especialidade, dt_diag
from organite_repository#linkB
/* ... */