Architecture Patterns with Python

Appendix D. Repository and Unit of Work Patterns with Django

Suppose you wanted to use Django instead of SQLAlchemy and Flask. How might things look? The first thing is to choose where to install it. We put it in a separate package next to our main allocation code:

├── src
│   ├── allocation
│   │   ├── __init__.py
│   │   ├── adapters
│   │   │   ├── __init__.py
...
│   ├── djangoproject
│   │   ├── alloc
│   │   │   ├── __init__.py
│   │   │   ├── apps.py
│   │   │   ├── migrations
│   │   │   │   ├── 0001_initial.py
│   │   │   │   └── __init__.py
│   │   │   ├── models.py
│   │   │   └── views.py
│   │   ├── django_project
│   │   │   ├── __init__.py
│   │   │   ├── settings.py
│   │   │   ├── urls.py
│   │   │   └── wsgi.py
│   │   └── manage.py
│   └── setup.py
└── tests
    ├── conftest.py
    ├── e2e
    │   └── test_api.py
    ├── integration
    │   ├── test_repository.py
...

Tip

The code for this appendix is in the appendix_django branch on GitHub:

git clone https://github.com/cosmicpython/code.git
cd code
git checkout appendix_django

Repository Pattern with Django

We used a plug-in called pytest-django to help with test database management.

Rewriting the first repository test was a minimal change—just rewriting some raw SQL with a call to the Django ORM/QuerySet language:

First repository test adapted (tests/integration/test_repository.py)

from djangoproject.alloc import models as django_models


@pytest.mark.django_db
def test_repository_can_save_a_batch():
    batch = model.Batch("batch1" ...