01intro.md

Introduction

Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design. It helps you build secure and maintainable websites quickly, so you can focus on writing your app without needing to reinvent the wheel. 🛠️

Why Use Django? 🤔

Advantages ✅

• Fast Development: Get your web application up and running quickly! ⏩
• Secure: Protects against common security threats by default. 🔒
• Scalable: Handles high traffic and large amounts of data gracefully. 📈
• Versatile: Suitable for all types of projects, from simple to complex. 🧩

Built-In Features (Batteries Included) 🔋

• Admin Interface: Automatically generated admin panel to manage your site.
• ORM: Object-Relational Mapping to interact with databases easily.
• Templating Engine: For dynamic HTML generation.
• Form Handling: Simplifies form rendering and validation.
• Authentication: User authentication system ready to go.

Real-World Examples 🌐

Websites that use Django:

• Instagram 📸
• Pinterest 📌
• Mozilla 🦊
• Khalti 💰
• National Geographic 🌍

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Understanding Django's Architecture 🏗️

Django follows the MVT (Model-View-Template) architectural pattern:

1. Model: Defines the data structure; it's the database layer. 🗄️
2. View: Contains the logic that interacts with the model and renders a response. 🧠
3. Template: Deals with the presentation layer; how data is displayed to the user. 🎨

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Key Principles 🎯

• DRY (Don't Repeat Yourself): Encourages reusability and clean code. ♻️
• Convention over Configuration: Makes decisions for you, so you can focus on your app. 📋
• Pluggable Apps: Easy to integrate third-party apps or create reusable ones. 🔌

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Alternatives to Django 🛣️

While Django is powerful, it's good to know other frameworks:

1. Flask 🧪
   • Lightweight and minimalistic.
   • Requires more configuration.
2. Laravel 🧙‍♂️
   • PHP framework with elegant syntax.
3. Ruby on Rails 💎
   • Based on Ruby, focuses on convention over configuration.

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Getting Started 🏁

Prerequisites 📋

1. Python 🐍
   • Make sure Python is installed on your system.
2. Virtual Environment 🌐
   • Isolates your project dependencies.
3. VS Code 💻
   • A powerful code editor.

Optional:

• Chrome Extension for Django 🧩
  • Enhances your development experience.

Setting Up Your Environment 🌳

Install Virtualenv

virtualenv

pip install virtualenv

To create virutal env

virtualenv myenv

Activate using bash

source myenv/Scripts/activate

pip install Django

3. Vs Code

Optional

• Chrome Extension For Django

How to Create First Project

Go to virtual env and run this command.

django-admin startproject myweekroutine

Run Project

python manage.py runserver 

Run on Different Port

python manage.py runserver 8181

Project File Structure

manage.py - A utility for interacting with Django project from command.

Inside myproject

settings.py - Setting files for your project. urls.py - Define URL routing for project. init.py - Marks this directory as python package. asgi.py Configuration for ASGI [Asynchronous Server Gateway Interface]

• wsgi.py - Configuration for WSGI [Web Server GateWay Interface] -- db.sqlite - Default SQlite database

Django App

Django app is web application that does one thing. For e.g. blog, ecommerce, forum, etc.

• Django project can contain multiple apps.
• Apps are reusable

How to Create Django App

python manage.py startapp <appname>

python manage.py startapp myapp

Project Vs App

• Project is overall configuration that ties multiple apps together.

• App is independent module/feature of project.

URL

Define URL routing for project.

• https://technologychannel.org/ - Root URL
• https://technologychannel.org/about/ - About URL

Views

Logic for handling request and returning response. It can be function or class.

Inside App

init.py - Marks this directory as python package. admin.py - Register models to apprear on Django admin interface. apps.py - Contain the configuration for app. models.py - Define Database models. tests.py - Used to write unit test for app. views.py - Logic for handling request and returning response. migrations/- Contains migration files for database changes.

Connect App to Project

• Open settings.py and find INSTALLED_APPS list.
• Add your new app to the list.

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'myapp',
]

How to Define Views

To define views first you need to import:

from django.http import HttpResponse

def index(request):
    return HttpResponse("<h1> Welcome to My Website </h1>")

def contact(request):
    return HttpResponse("<h1>Welcome to Contact Page</h1>")

After Define views What to do?

Create file called urls.py and add urls.

from . import views
from django.urls import path

urlpatterns = [
    path('',views.index,name='homepage'),
    path('contact',views.contact,name='contactpage'),
]

Define App Views To Project

First go to project's urls.py and add the code:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('',include('myapp.urls')) # Add this
]

Run Project

python manage.py runserver 

Steps To Do While Create New Project

1. Create virtualenv

virtualenv myenv

2. Activate virtualenv

• On Windows [Bash]

source myenv/Scripts/activate

• On Mac

source myenv/bin/activate

3. Install Django

pip install django

4. Create Django Project

django-admin startproject myproject

5. Open Project on Vs Code and Activate Virtual Env
6. Create App

python manage.py startapp myapp

7. Register App

INSTALLED_APPS = [
    'myapp',
]

8. Define Views in App

from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.

def index(request):
    return HttpResponse("<h1> Welcome to My Website </h1>")

def contact(request):
    return HttpResponse("<h1>Welcome to Contact Page</h1>")

9. Create urls.py file in app directory and create urls.

from . import views
from django.urls import path

urlpatterns = [
    path('',views.index,name='homepage'),
    path('contact',views.contact,name='contactpage'),
]

10. Define App views to project First go to project's urls.py and add the code:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('',include('myapp.urls')) # Add this
]

11. Run Project

python manage.py runserver