DevTut

# Mongodb integration

# Connect to MongoDB

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

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

# Read a collection

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

# Update a document

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

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 multiple documents

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

# Simple connect

# Simple connect, using promises

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);
    });
    ```js

# Syntax

  • db.collection.insertOne(document, options(w, wtimeout, j, serializeFuntions, forceServerObjectId, bypassDocumentValidation), callback)
  • db.collection.insertMany([documents], options(w, wtimeout, j, serializeFuntions, forceServerObjectId, bypassDocumentValidation), callback)
  • db.collection.find(query)
  • db.collection.updateOne(filter, update, options(upsert, w, wtimeout, j, bypassDocumentValidation), callback)
  • db.collection.updateMany(filter, update, options(upsert, w, wtimeout, j), callback)
  • db.collection.deleteOne(filter, options(upsert, w, wtimeout, j), callback)
  • db.collection.deleteMany(filter, options(upsert, w, wtimeout, j), callback)

# Parameters

Parameter Details
document A javascript object representing a document
documents An array of documents
query An object defining a search query
filter An object defining a search query
callback Function to be called when the operation is done
options (optional) Optional settings (default: null)
w (optional) The write concern
wtimeout (optional) The write concern timeout. (default: null)
j (optional) Specify a journal write concern (default: false)
upsert (optional) Update operation (default: false)
multi (optional) Update one/all documents (default: false)
serializeFunctions (optional) Serialize functions on any object (default: false)
forceServerObjectId (optional) Force server to assign _id values instead of driver (default: false)
bypassDocumentValidation (optional) Allow driver to bypass schema validation in MongoDB 3.2 or higher (default: false)

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