Django Notes (Python 3.5.1 and Django 1.9.x)

getting-started.md

Getting Started

Install Python, follow the steps here.

Steps I take when beginning a new Django project.

$ mkdir [project_name]_project
$ cd [project_name]_project

$ ~/local/python-3.5.1/bin/pyvenv env
$ . env/bin/activate

$ pip install django
$ pip freeze > requirements.txt

$ django-admin startproject [project_name]

$ touch .gitignore

Contents of the .gitignore file.

db.sqlite3
env
*.pyc

Before making anymore changes test that it works and then put everything under version control.

# Test it out
$ cd [project_name]
$ python manage.py migrate
$ python manage.py runserver
# View the site at http://127.0.0.1:8000/

# Version it
$ git init
$ git add --all
$ git commit -m "Initial commit"

Now change the database and timezone settings in [project_name]_project/[project_name]/[project_name]/settings.py.

Prerequisites

1. Install psycopg2 with $ pip install psycopg2. See here for more details.
2. Create the database in PostgreSQL, say [project_name]_development, with $ createdb -O [user] [project_name]_development.

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': '[project_name]_development',
        'USER': '[user]',
        'PASSWORD': '********',
        'HOST': 'localhost',
        'PORT': '5432'
    }
}

TIME_ZONE = 'America/Port_of_Spain'

Tip: If you want to connect without specifying a user and password then use the following setting.

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': '[project_name]_development'
    }
}

Without specifying a HOST psycopg2 will connect using a Unix socket in the same manner as psql. When you specify a HOST, psycopg2 will connect with TCP/IP, which requires a password. (ref)

• DATABASES
• TIME_ZONE

Now, we can migrate the db, create a super user, start the server and view the admin page to see that everything was set up correctly.

$ python manage.py migrate
$ python manage.py createsuperuser
$ python manage.py runserver

View the admin page at http://localhost:8000/admin.

• migrate
• createsuperuser
• runserver

Update your requirements.txt file and finally commit your changes at this point.

$ pip freeze > requirements.txt
$ git add --all
$ git commit -m "Configure a PostgreSQL database and set the timezone"

• requirements.txt

heroku.md

Heroku

This covers the changes that need to be made to the project to deploy to Heroku.

Install and configure the Heroku Toolbelt.

Install gunicorn

$ pip install gunicorn

and add a Procfile.

web: cd [project_name] && gunicorn [project_name].wsgi --log-file -

Update the database configuration to use an environment variable $DATABASE_URL.

$ pip install dj_database_url

# Update database configuration with $DATABASE_URL.
import dj_database_url
db_from_env = dj_database_url.config(conn_max_age=500)
DATABASES['default'].update(db_from_env)

Place the following in .env in [project_name]_project. Add to .gitignore as well.

DATABASE_URL=postgres:///hello_world_development

Update your static files settings.

PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__))

STATIC_ROOT = os.path.join(PROJECT_ROOT, 'staticfiles')
STATIC_URL = '/static/'

# Extra places for collectstatic to find static files.
STATICFILES_DIRS = (
    os.path.join(PROJECT_ROOT, 'static'),
)

Add staticfiles to .gitignore as well. Here's the updated .gitignore.

db.sqlite3
env
staticfiles
.env
*.pyc

Set up Django to serve static files in production.

Install whitenoise.

$ pip install whitenoise

In settings.py add the following,

# Simplified static file serving.
# https://warehouse.python.org/project/whitenoise/

STATICFILES_STORAGE = 'whitenoise.django.GzipManifestStaticFilesStorage'

Then, in wsgi.py do the following,

import os
 
from django.core.wsgi import get_wsgi_application
from whitenoise.django import DjangoWhiteNoise
 
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "hello_world.settings")
 
application = get_wsgi_application()
application = DjangoWhiteNoise(application)

Test it all out.

# Test static files collection, ensure when you deploy that this would run smoothly
$ python manage.py collectstatic --noinput

# Test running the app locally
$ heroku local web

Freeze your requirements.

$ pip freeze > requirements.txt

Tell Heroku that you're using Python 3.5.1. Add a runtime.txt file with the following contents.

python-3.5.1

Here are the supported Python versions.

References

• Python on Heroku
• Configuring Django Apps for Heroku
• Deploying Python and Django Apps on Heroku
• Django and Static Assets
• Specifying a Python Runtime

tools.md

Tools

• pip
• Virtual Environments and Packages