Python Django Classroom Series – 25/Aug/2021

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.

Preview

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 Preview

    • 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 Preview
  • 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 Preview

  • 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

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