Django App Workflow

django-app-workflow.md

Django App Workflow

last updated: 2 May 2024

Note: Replace all following instances of <project-name> with the name of your current project

Django Installation

Ref: https://tutorial.djangogirls.org/en/django_installation/

Virtual Environment

1. Create your project directory and change into it:

   mkdir <directory-name>
   cd <directory-name>
   

2. Create a virtualenv:

   python -m venv <venv-name>
   

   • It's a good idea to keep the venv name short, as you'll be referencing it a lot
3. Start your virtual environment by running:

   source <venv-name>/bin/activate
   

   • You will know you have virtualenv started when you see the propmp in your console is prefixed with (myvenv)
   • When working within a virtual environment, python will authomatically refer to the correct version, so you can use python instead of python3

Install Django

1. Make sure you have the latest version of pip, the software used to install Django:

   python -m pip install --upgrade pip
   

2. Create a requirements.txt file in the root project directory and add the following text "Django~=3.2.10"
3. Install Django:

   pip install -r requirements.txt
   

Start a New Django Project

Ref: https://tutorial.djangogirls.org/en/django_start_project/

1. Run the following command:

   django-admin startproject <project-name> .
   

2. You should now have a directory structure that looks like this:

   <directory-name>
   ├── manage.py
   ├── <project-name>
   │   ├── __init__.py
   │   ├── asgi.py
   │   ├── settings.py
   │   ├── urls.py
   │   └── wsgi.py
   ├── <venv-name>
   │   └── ...
   └── requirements.txt
   

   • manage.py serves as your project management script. It is used to create applications, work with databases, and start the development web server.
   • settings.py contains all the website settings, including registering any applications we create, the location of our static files, database configuration details, etc.
   • urls.py defines the site URL-to-view mappings. While this could contain all the URL mapping code, it is more common to delegate some of the mappings to particular applications, as you'll see later.
   • wsgi.py is used to help your Django application communicate with the web server. You can treat this as boilerplate.
   • asgi.py is a standard for Python asynchronous web apps and servers to communicate with each other. Asynchronous Server Gateway Interface (ASGI) is the asynchronous successor to Web Server Gateway Interface (WSGI). ASGI provides a standard for both asynchronous and synchronous Python apps, whereas WSGI provided a standard for synchronous apps only. ASGI is backward-compatible with WSGI and supports multiple servers and application frameworks.

Change Settings

Ref: https://tutorial.djangogirls.org/en/django_start_project/#changing-settings

1. Configure your timezone: open <my-project>/mysite/settings.py, find the line that contains TIME_ZONE and modify it with your own timezone. For example:

   TIME_ZONE = 'America/New_York'

2. Add a path for static files: go to the end of <my-project>/mysite/settings.py and, just underneath STATIC_URL, add a new entry called STATIC_ROOT:

   STATIC_URL = '/static/'
   STATIC_ROOT = BASE_DIR / 'static'

3. When DEBUG is True and ALLOWED_HOSTS is empty, the host is validated against ['localhost', '127.0.0.1', '[::1]']. This won't match the hostname once you deploy your application, so change the following setting:

   ALLOWED_HOSTS = ['127.0.0.1', '<host-name>']

Set Up a SQLite3 Database

Ref: https://tutorial.djangogirls.org/en/django_start_project/#set-up-a-database

1. sqlite3 is the default database software. Reference <project-name>/settings.py:

   DATABASES = {
       'default': {
           'ENGINE': 'django.db.backends.sqlite3',
           'NAME': BASE_DIR / 'db.sqlite3',
       }
   }

2. Create a database:

   python manage.py migrate
   

3. If the previous command goes well, you should see something like this:

   (myvenv) ~/djangogirls$ python manage.py migrate
   Operations to perform:
     Apply all migrations: admin, auth, contenttypes, sessions
   Running migrations:
     Applying contenttypes.0001_initial... OK
     Applying auth.0001_initial... OK
     Applying admin.0001_initial... OK
     Applying admin.0002_logentry_remove_auto_add... OK
     Applying admin.0003_logentry_add_action_flag_choices... OK
     Applying contenttypes.0002_remove_content_type_name... OK
     Applying auth.0002_alter_permission_name_max_length... OK
     Applying auth.0003_alter_user_email_max_length... OK
     Applying auth.0004_alter_user_username_opts... OK
     Applying auth.0005_alter_user_last_login_null... OK
     Applying auth.0006_require_contenttypes_0002... OK
     Applying auth.0007_alter_validators_add_error_messages... OK
     Applying auth.0008_alter_user_username_max_length... OK
     Applying auth.0009_alter_user_last_name_max_length... OK
     Applying auth.0010_alter_group_name_max_length... OK
     Applying auth.0011_update_proxy_permissions... OK
     Applying auth.0012_alter_user_first_name_max_length... OK
     Applying sessions.0001_initial... OK
   

Start the Web Server

Ref: https://tutorial.djangogirls.org/en/django_start_project/#starting-the-web-server

1. From the root directory (the one that contains manage.py), start the web server:

   python manage.py runserver
   

2. The web server is live now at http://127.0.0.1:8000/

Create an Application

Ref: https://tutorial.djangogirls.org/en/django_models/

1. Create an application:

   python manage.py startapp <app-name>
   

2. Notice a new <app-name> directory has been created and contains a number of files. The project file structure should now look like this:

   <directory-name>
   ├── <app-name>
   │   ├── admin.py
   │   ├── apps.py
   │   ├── __init__.py
   │   ├── migrations
   │   │   └── __init__.py
   │   ├── models.py
   │   ├── tests.py
   │   └── views.py
   ├── db.sqlite3
   ├── manage.py
   ├── <project-name>
   │   ├── asgi.py
   │   ├── __init__.py
   │   ├── settings.py
   │   ├── urls.py
   │   └── wsgi.py
   ├── <venv-name>
   │   └── ...
   └── requirements.txt
   

   • The tool creates a new folder and populates it with files for the different parts of the application (shown in the following example). Most of the files are named after their purpose (e.g. views should be stored in views.py, models in models.py, tests in tests.py, administration site configuration in admin.py, application registration in apps.py) and contain some minimal boilerplate code for working with the associated objects.
   • migrations folder stores "migrations" – files that allow you to automatically update your database as you modify your models.
   • __init__.py is an empty file created here so that Django/Python will recognize the folder as a Python Package and allow you to use its objects within other parts of the project.
3. Register the application with the project so that it will be included when any tools are run (like adding models to the database, for exmple). In mysite/settings/py, find INSTALLED_APPS and add a line containing <app-name>, to the end of the list.

   INSTALLED_APPS = [
       'django.contrib.admin',
       'django.contrib.auth',
       'django.contrib.contenttypes',
       'django.contrib.sessions',
       'django.contrib.messages',
       'django.contrib.staticfiles',
       '<app-name>',
   ]

Django Models

Ref: https://tutorial.djangogirls.org/en/django_models/

1. Create your model files in <app-name>/models.py
2. Add your new models to the database:

   python manage.py makemigrations <app-name>
   python manage.py migrate <app-name>
   

   • The makemigrations command creates (but does not apply) the migrations for all applications installed in your project. You can specify the application name as well to just run a migration for a single app.
   • The migrate command is what applies the migrations to your database. Django tracks which ones have been added to the current database.
   • You should re-run migrations whenever you make significant changes.

Django Admin

Ref: https://tutorial.djangogirls.org/en/django_admin/

1. In order to make your models visible on the admin page, open blog/admin.py and replace its contents with the following:

   from django.contrib import admin
   from .models import <Model-Name>
   
   admin.site.register(<Model-Name>)

2. Create a superuser – a user account that has control over everything on the site:

   python manage.py createsuperuser
   

3. Follow the prompts to enter your username (lowercase, no spaces), email address, and password. For example:

   Username: matt
   Email address: matt@example.com
   Password:
   Password (again):
   Superuser created successfully.
   

4. Make sure the web server is running (python manage.py runserver) and go to http://127.0.0.1:8000/admin/ in the browser, and enter your login information.