Django

Django is primarily a web development framework
designed to help developers build secure, scalable, and database-driven web applications quickly using Python
Features:
1. It provides all the necessary components for building a backend or full-stack application.
2. Includes an Object-Relational Mapper (ORM) for databases, user authentication, URL routing
3. Automatic admin panel
4. extends Python’s built-in unittest module for testing

Create, Run Django Project


// Create python venv
$ python3 -m venv .venv && source .venv/bin/activate && python --version && which python && pip --version
Python 3.10.12

// Install Django
$ python -m pip install Django

// Create Project
$ django-admin startproject my_tennis_club
$ ls
my_tennis_club
    manage.py
    my_tennis_club/
        __init__.py
        asgi.py
        settings.py
        urls.py
        wsgi.py

// Run the project
$ cd my_tennis_club
$ python manage.py runserver
Starting development server at http://127.0.0.1:8000/

Terms

App

An app is a web application that has a specific meaning in django project, like a home page, a contact form, or a members database.
django project has to be stopped while creating an app
Create app inside django project, representing tennis club members:


(.venv) my_tennis_club$ python manage.py startapp members
$ ls -ltr
total 12
-rwxr-xr-x 1 amit amit  665 Jul  4 10:11 manage.py
drwxr-xr-x 3 amit amit 4096 Jul  4 10:12 test_proj
-rw-r--r-- 1 amit amit    0 Jul  4 10:12 db.sqlite3
drwxr-xr-x 3 amit amit 4096 Jul  4 10:15 test_app
$ ls my_tennis_club/
__init__.py  admin.py  apps.py  migrations  models.py  tests.py  views.py

Views

Django views are Python functions that take http requests and return http response


$ cat members/views.py
from django.shortcuts import render
from django.http import HttpResponse

def members(request):
    return HttpResponse("Hello world!")

URLs (Router)

These files defines the path. URL -> project urls.py -> app urls.py -> view function -> response.

Top/Project Level Router


$ cat my_tennis_club/my_tennis_club/urls.py
from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('', include('members.urls')),    # Include App(members) urls
    path('admin/', admin.site.urls),
]

App Level Router


$ cat my_tennis_club/members/urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('members/', views.members, name='members'),  # path /members goto views
]

View is the responder


$ cat my_tennis_club/members/views.py
from django.shortcuts import render
from django.http import HttpResponse

def members(request):
    return HttpResponse("Hello world!")

Templates

In Django, the result should be in HTML, and it should be created in a template. Create a templates folder inside the members folder, and create a HTML file named myfirst.html


my_tennis_club
    manage.py
    my_tennis_club/
    members/
        templates/
            myfirst.html


$ cat my_tennis_club/members/templates/myfirst.html
<!DOCTYPE html>
<html>
<body>
<h1>Hello World! </h1>
<p >Welcome to my first Django project! </p>
</body>
</html>

Modify the view and route


$ my_tennis_club/members/views.py

from django.http import HttpResponse
from django.template import loader
def members(request):
  template = loader.get_template('myfirst.html')  <<<<<<
  return HttpResponse(template.render())

Change the settings


$ my_tennis_club/my_tennis_club/settings.py

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


$ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  ..


$ python manage.py runserver

Open 127.0.0.1:8000/members/

Database

When we created the Django project, we got an empty SQLite database. It was created in the root folder, and has the filename db.sqlite3.


$ sqlite3 db.sqlite3
SQLite version 3.37.2 2022-01-06 13:25:41
Enter ".help" for usage hints.
sqlite> .tables                          < These are default created tables
auth_group                  auth_user_user_permissions
auth_group_permissions      django_admin_log
auth_permission             django_content_type
auth_user                   django_migrations
auth_user_groups            django_session

Model = Table

By default, all Models created in the Django project will be created as tables in this database. Models = Tables in DB
Creating a Model = Table


$ vim my_tennis_club/members/models.py
from django.db import models

class Member(models.Model):           #class name = Table Name
  firstname = models.CharField(max_length=255)
  lastname = models.CharField(max_length=255)

makemigrations: Create Migration Script


my_tennis_club$ python manage.py makemigrations members
Migrations for 'members':
  members/migrations/0001_initial.py
    + Create model Member

my_tennis_club$ cat members/migrations/0001_initial.py
from django.db import migrations, models
class Migration(migrations.Migration):
    initial = True
    dependencies = [
    ]
    operations = [
        migrations.CreateModel(
            name='Member',
            fields=[
                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('firstname', models.CharField(max_length=255)),
                ('lastname', models.CharField(max_length=255)),
            ],
        ),
    ]

migrate: Run Migration script. Create Table.


my_tennis_club$ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, members, sessions
Running migrations:
  Applying members.0001_initial... OK

View Table.


python manage.py sqlmigrate members 0001

BEGIN;
--
-- Create model Member
--
CREATE TABLE "members_member" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "firstname" varchar(255) NOT NULL, "lastname" varchar(255) NOT NULL);
COMMIT;

Insert, Update, Delete data in Table

Insert


$ python manage.py shell

Python 3.10.12 (main, Mar  3 2026, 11:56:32) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from members.models import Member
>>> Member.objects.all()
<QuerySet []>

>>> member = Member(firstname='Emil', lastname='Refsnes')
>>> member.save()
>>> Member.objects.all().values()
<QuerySet [{'id': 1, 'firstname': 'Emil', 'lastname': 'Refsnes'}]>

Update


>>> Member.objects.all().values()
<QuerySet [{'id': 1, 'firstname': 'Emil', 'lastname': 'Refsnes'}]>
>>> x = Member.objects.all()[0]
>>> x.firstname
'Emil'

>>> x.firstname = "Stalikken"
>>> x.save()

>>> Member.objects.all().values()
<QuerySet [{'id': 1, 'firstname': 'Stalikken', 'lastname': 'Refsnes'}]>

Delete


>>> x = Member.objects.all()[0]
>>> x.firstname
'Stalikken'
>>> x.lastname
'Refsnes'

>>> x.delete()
(1, {'members.Member': 1})
>>> Member.objects.all().values()
<QuerySet []>
>>>

Update Model: Add 2 new fields


$ vim members/models.py
from django.db import models

class Member(models.Model):
  firstname = models.CharField(max_length=255)
  lastname = models.CharField(max_length=255)
  phone = models.IntegerField(null=True)
  joined_date = models.DateField(null=True)

$ python manage.py makemigrations members
Migrations for 'members':
  members/migrations/0002_member_joined_date_member_phone.py
    + Add field joined_date to member
    + Add field phone to member

// Apply 0002_member_joined_date_member_phone.py
$ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, members, sessions
Running migrations:
  Applying members.0002_member_joined_date_member_phone... OK