Django 4 Instant Customer Database Tutorial

Build a customer database. Web interface. Multiple users can log in, and edit customer database.

Learn the basics of Django 4, the web framework used by Instagram, National Geographic and Discus.

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Prerequisites

You should have Linux installed. I've tested with Debian 11-Bullseye, but you can adapt to others.

You should know Linux command line.

Install development environment

$ sudo apt-get -y install virtualenv

Create a new virtualenv to install latest versions of Python packages, such as Django 4.

$ virtualenv --system-site-packages -p python3 env/

This creates new folder env/, that will have the latest packages in lib/site-packages/. We of course want to use Python version 3. Some Python packages are much more convenient to install with apt-get, so --system-site-packages allows using packages outside virtual environments.

Let's use our new virtual environment

$ source env/bin/activate

Prompt probably shows "(env)" in the beginning. Virtualenv is not a security feature or a sandbox. Any Python packages you install inside it need per-program consideration.

Make sure we're installing to virtual environment. Don't use pip without virtualenv, and definetly don't run pip with sudo.

$ which pip
/home/tero/env/bin/pip

Let's list our single Python package in a text file

$ sudo apt-get install micro
$ micro requirements.txt # "django" ctrl-S saves, ctrl-Q quits

$ cat requirements.txt
django

$ pip install -r requirements.txt

Did we get the latest Django?

$ django-admin --version
4.0.2

Well done.

Hello DJ Ango!

Your whole website is a project in Django.

$ django-admin startproject teroco

Let's try it

$ cd teroco
$ ./manage.py runserver   # development server, do not expose to the internet
Starting development server at http://127.0.0.1:8000/

So, let's browse to the URL. Can you see the welcome page? Great, you're running the development server of Django.

Admin interface - for free

Let's add /admin to the URL. http://127.0.0.1:8000/admin/

There is a login interface, but we can't yet get in.

Update the databases

$ ./manage.py makemigrations
$ ./manage.py migrate

And add a user

$ sudo apt-get install pwgen
$ pwgen -s 20 1 # randomize a password

$ ./manage.py createsuperuser

Now try loggin in a again http://127.0.0.1:8000/admin/ .

Can you see the admin view? Well done, you're using Django admin interface.

Add More Users

Add a user. Make this new user staff and superuser, so he can modify any data trough the web admin interface. Remember to use a good password.

Log out from web admin, and log in as your new user.

Can you modify data? Well done, you now have a new web admin user.

Create a Customer Database

$ ./manage.py startapp crm

This created a new folder crm/ for our Customer Relationship Management app.

Add the app to INSTALLED_APPS in settings.py.

$ micro teroco/settings.py

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'crm', # add this
]

Let's add some models. Django can automatically create databases, admin views and even forms from the models.

$ micro crm/models.py 

from django.db import models

class Customer(models.Model):
   name = models.CharField(max_length=300)

So, Customer class will create a "customer" table in the database, with "name" column.

$ ./manage.py makemigrations
$ ./manage.py migrate

To see our new database in admin/, we must register it.

$ micro crm/admin.py

from django.contrib import admin
from . import models

admin.site.register(models.Customer)

Let's see our new Customer model in the admin.

$ ./manage.py runserver

Log into http://127.0.0.1:8000/admin/ .

Can you see Customers? Add some customers, modify them and remove them. Well done!

List Their Names

Customer names are currently listed in pretty annoyingly: "Customer object (1)", "Customer object (2)"... I'm not a number, I'm a free man!

Let's make the admin interface show our customer's names also in list. Edit the existing models.py, where we've described Customer class.

$ micro crm/models.py

from django.db import models

class Customer(models.Model):
    name = models.CharField(max_length=160)

    def __str__(self):		# new
        return self.name	# new

Now we can tell how Customer is converted to string. The name of the function is funny, two underscrores on each side. Python objects refer to themselves as "self", similar to "this" in some other languages. You can return any string, but customer's name is better than "potato".

Well Done!

You now have

  • A customer database
  • A web admin interface to edit the database
  • The admin interface is protected by password for each user

Next, we could put this to production. You must never expose the development server (runserver) to the internet. For production, we'll use Apache. It's the most popular web server in the whole world!

Adminstrivia

This article has been updated multiple times.