The document describes the Model-View-Controller (MVC) architecture. MVC separates an application into three main components: the model manages the data logic and rules; the view displays the data to the user; and the controller handles input and converts it to commands for the model and view. Specifically, the model defines the data structures, the view displays the data, and the controller mediates the interaction between the model and view, such as retrieving data from the model and passing it to the view to display.

1. MVC
Model View Controller

2. MVC purpose?
● An architecture for separating
components of a large code block by
abstracting components of a large code
base into smaller manageable pieces.
● Can be used to structure code of any language

3. MVC components?
● Model - database management
● View - user interface
● Controller - logic for user requests

5. Model purpose?
● The model in MVC architecture is responsible
for manipulating the data.
● Structuring data.
● Inserting, deleting, updating…
● Never interacts with the view directly

6. Model example
● The model will define what an acceptable piece of data
should look like.
● Any piece of data not adhering to the model structure
should not be allowed into the database.
Model
Student {
Name: String
Class: String,
Grade: Number,
}
Valid
Student {
Name: “Bob”,
Class: “Math”,
Grade: 80,
}
Not Valid
Student {
ID: 808,
Class:501 ,
Grade: “Pass”,
}

7. Model using mongoose schema
const mongoose = require(‘mongoose’);
const StudentSchema = new mongoose.Schema({
Name:{ Type: String },
Class:{Type: String},
grade:{Type: Number}
})
Module.exports = mongoose.model(‘Student’, StudentSchema)

8. View purpose?
● The view is responsible for displaying the
data
● The view never interacts directly with the
model, instead the controller proxys any
data the view may need

9. View examples
Views provide the user interface in the MVC
architecture and can be simple html or
template engines like EJS and Express-
Handlebars
<%= EJS %>

10. Controller
● Can be more than one controller in a
project
● Each controller has a specific route or
responsibility with a particular resource

11. Controller purpose?
● Handles any logic required from user
requests
● The controller acts as a hub for user
requests through the view and retrieval or
modification of the database by way of the
model

12. Controller answering a request from the
user
//inventory router directs request to applicable
controllers
Router.get('/',inventoryController.getInventory)
Router.post('/', inventoryController.addPart)
● Router has determined controllers responsible for
specific resources to handle requests

13. const Parts = require("../models/Part");//MODEL
module.exports.getInventory = async (req,res)=>{
//requesting parts from MODEL
const allInventory = await Parts.find()
//VIEW response
res.render('inventory.ejs',{inventory:allInventory})
}
● Controller has ability to query the model for any data
necessary to fulfill the request given by the router
● Once any logic necessary is complete, the view is
provided with any necessary data and then presents
the user with an interface to interact with.
Controller example

14. student.ejs
MONGODB
/controller/student.js
Const Student =
require(‘./models/student’)
Module.exports.getStudents =
(req,res)=> {
Const allStudents = Student.find();
res.render(students.ejs,{students:allstu
dents})
}
MONGOOSE
./models/student
Server.js
Const studentRoutes=
require(‘./routes/student.js’)
app.use(‘/inventory’,studentRoutes)
/routes/student.js
Const studentCtr=
require(‘./controller/student.js’)
app.get(‘/’, studentCtr.getStudents)