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Django Create Model

Learn how to manage a new model in Django - free sample included.

This page explains how to create and USE a model in Django. All commands used to code the project and also the relevant updates are listed below. For newcomers, Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. Built by experienced developers, it takes care of much of the hassle of Web development, so you can focus on writing your app without needing to reinvent the wheel.

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How to code this sample​

This sample can be coded from scratch by following the steps below.

Check Python Version

$ python --version
Python 3.8.4 <-- All good

Create/activate a virtual environment - Unix-based system

$ # Virtualenv modules installation
$ virtualenv env
$ source env/bin/activate

For Windows, the syntax is slightly different

$ # virtualenv env
$ # .\env\Scripts\activate

Install Django (the latest stable version)

$ pip install django

Create a new Django Project

$ mkdir django-sample-urls
$ cd django-sample-urls

Inside the new directory, we will invoke startproject subcommand

$ django-admin startproject config .

Note: Take into account that . at the end of the command.

Setup the database

$ python manage.py makemigrations
$ python manage.py migrate

Start the app

$ python manage.py runserver
$
$ # Access the web app in browser: http://127.0.0.1:8000/

At this point we should see the default Django page in the browser:

Django - Default Project Page.

Create a new Django app

$ python manage.py startapp sample

Visualize the default SQL settings - config/settings.py

# File: config/settings.py (partial content)
...
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}
...

Define a new model Books in sample application. The below changes should be added to sample/models.py:

# File: sample/models.py

from django.db import models

class Book(models.Model):                                 # <- NEW
    title            = models.CharField(max_length=100)   # <- NEW
    author           = models.CharField(max_length=100)   # <- NEW
    publication_date = models.DateField()                 # <- NEW

Tip - for a quick check over the latest changes we can run check subcommand.

$ python manage.py check
System check identified no issues (0 silenced).

Generate the SQL code (migrate the database).

$ python manage.py makemigrations  # generate the SQL code
Migrations for 'sample':
  sample\migrations\0001_initial.py
    - Create model Book

Apply changes on the database

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

Use the model via CLI

Once the model is created we can use it via the Django shell:

$ python manage.py shell
>>>
>>> from sample.models import Book     # import the Book model in our context
>>> from django.utils import timezone  # used to provide the value for publication_date
>>>
>>> book1 = Book(title='The Adventures of Tom Sawyer', author='Mark Twain', publication_date=timezone.now() )
>>> book1.save()                       # save the new book

List all books (using the CLI)

$ python manage.py shell
>>>
>>> from sample.models import Book
>>> Book.objects.all()
<QuerySet [<Book: Book object (1)>]>

We can see our new book returned by the query. Let's improve the information that describes the object.

Django Model - add text representation of an object

To achieve this goal, we should define the __str__() method for the Book model

# File: sample/models.py

from django.db import models

class Book(models.Model):
    title            = models.CharField(max_length=100)
    author           = models.CharField(max_length=100)
    publication_date = models.DateField()

    def __str__(self):       # <- NEW
        return self.title    # <- NEW

Let's restart the Django console and check the results:

$ python manage.py shell
>>>
>>> from sample.models import Book
>>> Book.objects.all()
<QuerySet [<Book: The Adventures of Tom Sawyer>]>

Use the model via Admin Section

Django comes with an admin section out-of-the-box that allows us to manage with ease all models defined in the project. To manage the Book model in the administration console we need to create a superuser (aka the admin) and after register the Book model to be visible in the admin section.

Create the superuser

$ python manage.py createsuperuser
sername (leave blank to use 'sm0ke'): admin
Email address: admin@appseed.us
Password:
Password (again):
Superuser created successfully.

Register Book model to be visible in the admin section - Edit sample/admin.py as below:

# File: sample/admin.py

from django.contrib import admin

from .models import Book        # <- NEW

admin.site.register(Book)       # <- NEW

Authenticate as admin - http://localhost:8000/admin/

At this point, we should see the Books model in the UI and able to execute CRUD operations.

Create Django Model - Admin Interface.

Create Django Model - List Model Items

Django Create Model - Edit Model Item

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