Mongodb: Count

const {MongoClient, ObjectId} = require('mongodb');

const URL = 'mongodb://localhost:27017/<my_app>';

MongoClient.connect(URL, (err, db) => {

if (err) {
return console.log('Unable to connect to mongo db.', err);
}

console.log('Connected to mongo db.');

db.collection('<my_table>').find({
   // Object search criteria as an object    // {
   // attribute1: atribute1Value,
   // ...
   // attributeN: atributeNValue
   // }
}).count().then((count) => {
console.log(JSON.stringify(todos, undefined, 2));

}, (err) => {
console.log('unable to fetch todos', err);
});
});

Mongodb: Insert

Insert

const {MongoClient} = require('mongodb');

const URL = 'mongodb://localhost:27017/<my_app>';

MongoClient.connect(URL, (err, db) => {

if (err) {
return console.log('Unable to connect to mongo db.');
}

console.log('Connected to mongo db.');

db.collection('<my_table>').insertOne({
// Your object
}, (err, result) => {
if (err) {
return console.log('Unnable to insert todo.', err);
}

console.log(JSON.stringify(result.ops, undefined, 2)); // ops stores all the docs inserted
});

db.close();
});

Mongodb: Fetch

Find all

const {MongoClient, ObjectId} = require('mongodb');

const URL = 'mongodb://localhost:27017/<my_app>';

MongoClient.connect(URL, (err, db) => {

if (err) {
return console.log('Unable to connect to mongo db.', err);
}

console.log('Connected to mongo db.');

db.collection('<my_table>').find().toArray().then((docs) => {
console.log(JSON.stringify(todos, undefined, 2));

}, (err) => {
console.log('unable to fetch todos', err);
});
});

Perform search

const {MongoClient, ObjectId} = require('mongodb');

const URL = 'mongodb://localhost:27017/<my_app>';

MongoClient.connect(URL, (err, db) => {

if (err) {
return console.log('Unable to connect to mongo db.', err);
}

console.log('Connected to mongo db.');

db.collection('<my_table>').find({
   // Object search criteria as an object    // {
   // attribute1: atribute1Value,
   // ...
   // attributeN: atributeNValue
   // }
}).toArray().then((docs) => {
console.log(JSON.stringify(todos, undefined, 2));

}, (err) => {
console.log('unable to fetch todos', err);
});
});

Search by id

const {MongoClient, ObjectId} = require('mongodb');

...

db.collection('<my_table>').find({
   // Object search criteria as an object    // {
   // _id: new ObjectID(<objects_id>)
   // }
}).toArray().then((docs) => {
console.log(JSON.stringify(todos, undefined, 2));

}, (err) => {
console.log('unable to fetch todos', err);
});

});

Mongodb: Start server

1) Navigate to the folder where your mongo executables are (usually placed on user's folder)
2) Starts the server, creates an active connection to manipulate data:
./mongod --dbpath ~/mongo-data // Or whatever your folder name is
3) On another tab run:
./mongo // connects to the database

Mongodb: Object destructuring

Obtain variables from object properties.

var user = {name: ‘Andrew’, age: 25};var {name} = user;

Also

const {MongoClient} = require('mongodb');

is equal to 

const MongoClient = require('mongodb').MongoClient;