To connect to PostgreSQL using the Django framework it is necessary to install the dj-database-url package and add it in the dependency file called requirements.txt.

$ pip install dj-database-url
$ pip freeze > requirements.txt

Then add the following code at the bottom of settings.py file:

import dj_database_url 
DATABASES['default'] = dj_database_url.config()

In the deploy process, the DATABASE_URL variable will be parsed and converted into a form that Django can understand.