Model View Controller

• MVC stands for Model View and controller
  • Model: This porvides the interface for the data stored in databases
  • Views: This is an user interace. It is responsible for displaying Model data to the user and also take up information from users
  • Controller: A controller in MVC is responsible for the entire logic behind the web application.

Django MVT Architecture

• MVT Stands for Model view Template

  • Model: Just like the Model in the MVC, here we have some functionality of providing the interface for the data stored in database
  • Template: This is like View in MVC. Django uses templates in its framework. Templates are responsible for User Interface.
  • Views:
    • In Django Views act a link b/w Model data and templates
    • View will see the user request retrieves appropriate data from databases, then renders back the template along with retrieved data

• Control flow of MVT

  • User send a URL Request for a resource to Django
  • Django framework search for the URL resource
  • If the URL path links up to view, then particular view is called
  • View will interact with model and retrieve the appropriate data from database
  • The View then renders back an appropriate template along with the retrieved data to the user

• Lets Dive little bit more into this

Models

• Django models define the data for your application and provide an abstraction layer to SQL database access through Object Relational Mapper (ORM).
• ORM lets you define the data schema using python code, without needing to understand of the underlying database.
• This means we can define database layer in python code and Django will take care of generating SQL Queries for us.
• We can choose many SQL database servers such as SQLite, PostgreSQL, MySQL or Microsoft SQL Server
• Django’s ORM takes care of these differences for you.

Views

• A Django View is where most of the logic for our applciation is defined.
• A view is a function that we write which will receive the request (made by user from webbrowser) in the form of Python Object (Specifically, a Django HttpRequest Object).
• It is up to view to decide how it should respond to the request and what it should send back to the user.
• View should return an HttpResponse object

Templates

• A template is a HTML file that contains special placeholders that can be replaced with varibales your application provides.
• For example, if our application could render list of items , view would fetch the same models and render a HTML file with information fetched from models

Introduction to HTTP

• Web browser create an HTTP request, which is sent to the server hosting website

• Once the webserver recieves the HTTP request, it can interpret it and then sends back a response.

• The response that the server sends might be simple such as an HTML file or image etc.

• Request is made up of four main parts

  • Methods: HTTP protocol has methods, some of the common ones are
    • GET (retrieve the remote page/data)
    • POST (send data to the remote)
    • PUT (Create request with data)
    • DELETE (delte some resource)
  • path
  • headers: contain the data sent from browser to webserver, lets look at some of the most commn headers
    • Host
    • User-Agent
    • Cookie
    • Content-Type
    • Authentication Headers
  • body