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Topic 3: Introduction to Django: Building More Complex Web Applications

Python for All: Discover, Learn, and Master Lesson 11: Web Development with Python Topic 3: Introduction to Django: Building More Complex Web Applications

1. What is Django?

Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design. Coined as “the web framework for perfectionists with deadlines”, Django facilitates the creation of complex, database-driven websites with ease.

2. Why Django?

Batteries Included: Unlike Flask, Django follows a “batteries-included” philosophy, meaning it includes a wide array of built-in functionalities that web developers might need.
Admin Interface: One of Django’s most powerful features is its automatic admin interface, which provides a GUI to manage application data.
ORM (Object-Relational Mapping): Django comes with a high-level ORM that lets you define your database schema using Python classes.
Security: Django has built-in protections against many common web attacks like XSS, CSRF, and SQL Injection.
Scalability: High-profile platforms like Instagram and Pinterest utilize Django, showcasing its potential for scalability.

3. Setting up Django

Installation is straightforward using pip:

pip install django

To start a new project:

django-admin startproject projectname

4. Basic Structure of a Django App

A Django project comprises various apps (modules). Here’s a basic breakdown:

Project: The entire application and its configuration.
App: A module within the project (e.g., Blog, Store).
Models: Define the data structures.
Views: Handle the user interface and control flow.
Templates: HTML files blended with Django Template Language.
URLs: Map URLs to views.

5. A Simple Django Example

Let’s create a basic web page using Django.

First, create a new app:

python manage.py startapp myapp

Models (models.py):

python

from django.db import models

class Greeting(models.Model):
    text = models.CharField(max_length=200)

Views (views.py):

python

from django.http import HttpResponse
from .models import Greeting

def hello(request):
    greeting = Greeting(text="Hello, Django World!")
    return HttpResponse(greeting.text)

URLs (urls.py in your project directory):

python

from django.urls import path
from .views import hello

urlpatterns = [
    path('hello/', hello, name='hello'),
]

After setting up your database and running migrations, visiting /hello/ should display “Hello, Django World!”.

6. Expanding on Django’s Power: The Admin Interface

Once you’ve set up your models, you can easily integrate them with Django’s built-in admin site. First, you’ll need to create a superuser:

python manage.py createsuperuser

Then, in the admin.py of your app, you can register your models:

python

from django.contrib import admin
from .models import Greeting

admin.site.register(Greeting)

Now, by navigating to /admin/, you can manage your Greeting model instances through a user-friendly GUI.

7. What’s Next with Django?

Django’s ecosystem is vast. There’s a lot to explore, such as:

Forms: Django provides a powerful form library that handles rendering forms as HTML, validating user-submitted data, and converting that data to native Python types.
Class-Based Views: While our example used a function-based view, Django also supports class-based views, making it easier to reuse and modularize view behavior.
Middleware: Components that process requests and responses globally before they reach the view or after they leave the view.
Extensions: There are countless third-party packages designed for Django, further extending its capabilities.

Conclusion:

Django is a robust and versatile framework that’s well-suited for developers looking to build web applications without reinventing the wheel. Its modularity and wide array of built-in tools make it an excellent choice for both beginners and seasoned developers. Whether you’re building a blog, an e-commerce platform, or a social media site, Django provides the structure and tools to get you started efficiently.

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