Connect to MongoDB, print 'Connected!' and close the connection.

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

var url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function(err, db) { // MongoClient method 'connect'
    if (err) throw new Error(err);
    console.log("Connected!");
    db.close(); // Don't forget to close the connection when you are done
});

---

MongoClient method Connect()

MongoClient.connect(url, options, callback)

Argument	Type	Description
url	string	A string specifying the server ip/hostname, port and database
options	object	(optional) Optional settings (default: null)
callback	Function	Function to be called when the connection attempt is done

The callback function takes two arguments

• err : Error - If an error occurs the err argument will be defined
• db : object - The MongoDB instance

Insert a document called 'myFirstDocument' and set 2 properties, greetings and farewell

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

const url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function (err, db) {
  if (err) throw new Error(err);
  db.collection('myCollection').insertOne({ // Insert method 'insertOne'
    "myFirstDocument": {
      "greetings": "Hellu",
      "farewell": "Bye"
    }
  }, function (err, result) {
    if (err) throw new Error(err);
    console.log("Inserted a document into the myCollection collection!");
    db.close(); // Don't forget to close the connection when you are done
  });
});

---

Collection method insertOne()

db.collection(collection).insertOne(document, options, callback)

Argument	Type	Description
collection	string	A string specifying the collection
document	object	The document to be inserted into the collection
options	object	(optional) Optional settings (default: null)
callback	Function	Function to be called when the insert operation is done

The callback function takes two arguments

• err : Error - If an error occurs the err argument will be defined
• result : object - An object containing details about the insert operation

Get all documents in the collection 'myCollection' and print them to the console.

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

const url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function (err, db) {
  if (err) throw new Error(err);
  var cursor = db.collection('myCollection').find(); // Read method 'find'
  cursor.each(function (err, doc) {
    if (err) throw new Error(err);
    if (doc != null) {
      console.log(doc); // Print all documents
    } else {
      db.close(); // Don't forget to close the connection when you are done
    }
  });
});

---

Collection method find()

db.collection(collection).find()

Argument	Type	Description
collection	string	A string specifying the collection

Find a document with the property { greetings: 'Hellu' } and change it to { greetings: 'Whut?' }

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

const url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function (err, db) {
    if (err) throw new Error(err);
    db.collection('myCollection').updateOne({ // Update method 'updateOne'
        greetings: "Hellu" }, 
        { $set: { greetings: "Whut?" }},
        function (err, result) {
            if (err) throw new Error(err);
            db.close(); // Don't forget to close the connection when you are done
        });
});

---

Collection method updateOne()

db.collection(collection).updateOne(filter, update, options. callback)

Parameter	Type	Description
filter	object	Specifies the selection critera
update	object	Specifies the modifications to apply
options	object	(optional) Optional settings (default: null)
callback	Function	Function to be called when the operation is done

The callback function takes two arguments

• err : Error - If an error occurs the err argument will be defined
• db : object - The MongoDB instance

Delete a document with the property { greetings: 'Whut?' }

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

const url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function (err, db) {
    if (err) throw new Error(err);
    db.collection('myCollection').deleteOne(// Delete method 'deleteOne'
        { greetings: "Whut?" },
        function (err, result) {
            if (err) throw new Error(err);
            db.close(); // Don't forget to close the connection when you are done
    });
});

---

Collection method deleteOne()

db.collection(collection).deleteOne(filter, options, callback)

Parameter	Type	Description
filter	object	A document specifying the selection critera
options	object	(optional) Optional settings (default: null)
callback	Function	Function to be called when the operation is done

The callback function takes two arguments

• err : Error - If an error occurs the err argument will be defined
• db : object - The MongoDB instance

Delete ALL documents with a 'farewell' property set to 'okay'.

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

const url = 'mongodb://localhost:27017/test';

MongoClient.connect(url, function (err, db) {
    if (err) throw new Error(err);
    db.collection('myCollection').deleteMany(// MongoDB delete method 'deleteMany'
        { farewell: "okay" }, // Delete ALL documents with the property 'farewell: okay'
        function (err, result) {
            if (err) throw new Error(err);
            db.close(); // Don't forget to close the connection when you are done
    });
});

---

Collection method deleteMany()

db.collection(collection).deleteMany(filter, options, callback)

Parameter	Type	Description
filter	document	A document specifying the selection critera
options	object	(optional) Optional settings (default: null)
callback	function	Function to be called when the operation is done

The callback function takes two arguments

• err : Error - If an error occurs the err argument will be defined
• db : object - The MongoDB instance

MongoDB.connect('mongodb://localhost:27017/databaseName', function(error, database) {
   if(error) return console.log(error);
   const collection = database.collection('collectionName');
   collection.insert({key: 'value'}, function(error, result) {
      console.log(error, result);
   });
});

const MongoDB = require('mongodb');

MongoDB.connect('mongodb://localhost:27017/databaseName')
    .then(function(database) {
        const collection = database.collection('collectionName');
        return collection.insert({key: 'value'});
    })    
    .then(function(result) {
        console.log(result);
    });
    ```