This document provides an overview of building a MEHN stack application from scratch. It discusses MongoDB concepts like CRUD operations, schemas, and connecting MongoDB to an application. It also covers using Express and Handlebars for the application framework. The presenter will demonstrate a full CRUD application in MongoDB with Express and Handlebars over the next two days, starting from initializing the project and building out functionality.

1. MEHN STACK
By Narendranath Reddy
Day 1
Theory…

2. Name: Narendranath Reddy Thota
 d3 Whitepaper Core Team
 Trainer from Gama
 Blockchain Full Stack Developer
 Technology Analyst
 Software Developer
 Technology Speaker
MAERSK
Email: narendranath.thota@ust-global.com
P: +917288838869

3. AGENDA
Day 1: Full theory(MEHN) and mongodb practical
Day 2: Full practical developing code from scratch MEHN
Day3:
Brief explanation on How complex code is, if we doesn't use
handlebars JS in our app
some theory on popular java scripts and demo on vanilla
script.

5. NOSQL
• Key-value
• Graph database
• Document-oriented
• Column family

20. IN PRODUCTION
20
http://www.mongodb.org/about/production-deployments/

21. RDBMS MongoDB
Database Database
Table,
View
Collection
Row Document (JSON,
BSON)
Column Field
Index Index
Join Embedded
Document
Foreign
Key
Reference
Partition Shard
> db.user.findOne({age:39})
{
"_id" :
ObjectId("5114e0bd42…"),
"first" : "John",
"last" : "Doe",
"age" : 39,
"interests" : [
"Reading",
"Mountain Biking ]
"favorites": {
"color": "Blue",
"sport": "Soccer"}
}

22. CRUD
• Create
• db.collection.insert( <document> )
• db.collection.save( <document> )
• db.collection.update( <query>, <update>, { upsert: true } )
• Read
• db.collection.find( <query>, <projection> )
• db.collection.findOne( <query>, <projection> )
• Update
• db.collection.update( <query>, <update>, <options> )
• Delete
• db.collection.remove( <query>, <justOne> )
22
Projection?

23. INSERT VS
INSERTONE
• Insert
(deprecated)
• insertOne
• insertMany
MongoDB's update() and save() methods
are used to update document into a collection.
Update vs save
Update: changes an existing document found by
your find-parameters and does nothing when no
such document exist (unless you use the upsert =
true option).
Save: doesn't allow any find-parameters. It checks if
there is a document with the same _id as the one
you save exists. When it exists, it replaces it. When
no such document exists, it inserts the document as
a new one.

24. CRUD EXAMPLE
24
> db.user.insert({
first: "John",
last : "Doe",
age: 39
})
> db.user.find ()
{
"_id" : ObjectId("51…"),
"first" : "John",
"last" : "Doe",
"age" : 39
}
> db.user.update(
{"_id" : ObjectId("51…")},
{
$set: {
age: 40,
salary: 7000}
}
)
> db.user.remove({
"first": /^J/
})

25. FEATURES
• Document-Oriented storege
• Full Index Support
• Replication & High
Availability
• Auto-Sharding
• Querying
• Fast In-Place Updates
• Map/Reduce
25
Agile
Scalable
Auto-Sharding ?

26. INSTALLATION• https://www.mongodb.com/download-center#enterprise
• Two ways to start
• 1: Normal way
• mongodb –dbpath D:mongodatadb
• mongo
• 2: Background as a service
Command1: Mongod --directoryperdb –dbpath D:mongodatadb
--logpath D:mongologmongo.log –logappend –rest --install
Command 2: Net start MongoDB

27. LIVE DEMO IN MONGO CLIENT
•Mongodb major developer Operations
Better will do this in practical session slot

28. CONNECT MONGODB TO OUR APPvar url = "mongodb://localhost:27017/database-name";
var MongoClient =require('mongodb').MongoClient;
List All:
MongoClient.connect(url, function(err, db) {
var result = [];
if (err) throw err;
var cursor =db.collection('mehn').find({});
cursor.forEach(function(doc, err) {
result.push(doc);
}, function() {
db.close();
});
});

44. OTHER WAYS…
var express = require('express');
var app = express();
var server = app.listen(8085, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})

49. "plugins" known as middleware.
https://stephensugden.com/middleware_guide/

61. EXPRESS-HANDLEBARS
var express = require('express');
var path = require('path');
var app = express();
// View Engine
var exphbs = require('express-handlebars');
app.set('views', path.join(__dirname, 'views'));
app.engine('handlebars',exphbs({defaultLayout:'layout'}));
app.set('view engine', 'handlebars');
//end view Engine for handlebars

62. STEPS:
• 1) make new newfolder – npm init
• 2) mention all required packages in package.json
• 3) npm install
• 4) structure
• – views folder
• layouts folder
• layout(default)file
Home.handlebars-file
Login.handlebars-file
.
├── app.js
└── views
├── home.handlebars
└── layouts
└── main.handlebars
2 directories, 3 files

63. PACKAGE NAMES:
• "dependencies": {
• "body-parser": "*",
• "express": "*",
• "express-handlebars": "*",
• "file-system": "^2.2.2",
• "express-validator": "^4.2.1",
• "mongodb": "*",
• "node-dev": "^3.1.3" // Auto restart - server
• }

64. JAVASCRIPT
FRAMEWORKS

65. THANK YOU.
Day2 Practical Demo
From the scratch in front of you
CRUD Operation
Pre – requisites:
Nodejs v8
Mongo dB
Frameworks:
Express
HandlebarsJS