Connect Django to a Postgres database

To connect to a PostgreSQL database first make sure you have an environment variable called DATABASE_URL set to the URL of your database.

DATABASE_URL=postgres://user:password@127.0.0.1:5432/database_name

Hosts like Heroku will automatically set this when you provision the database; providing you are using Heroku Postgres¹.

If you are working locally and using Pipenv you can set the config for DATABASE_URL in a .env file and it will load the .env as part of your virtual environment².

Install the required package

To use PostgreSQL as your database in Python applications you must use the psycopg2 package³.

pipenv install psycopg2-binary

Connecting in Python

import os
import psycopg2

db = psycopg2.connect(os.environ['DATABASE_URL'], sslmode='require')

Connecting in Django

Update the connection details in settings.py, making sure to import os and urlparse from the standard library.

# settings.py
import os
from urllib.parse import urlparse

db = urlparse(os.environ['DATABASE_URL'])
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': db.path.strip('/'),
        'USER': db.username,
        'PASSWORD': db.password,
        'HOST': db.hostname,
        'PORT': db.port,
    }
}

Using a package to simplify

As an alternative to the above there is a package available called dj_database_url ⁴. This package parses the value of the DATABASE_URL environment variable and converts it to a dictionary that Django can use.

pipenv install dj-database-url psycopg2-binary

# settings.py
import dj_database_url

DATABASES['default'] = dj_database_url.config(conn_max_age=600, ssl_require=True)