Let's talk about some concepts from API-First, and how to apply them to a Django-powered environment. We'll mention GraphQL, of course.

1. API-First Design
and Django
The tale of caring for your fellow developer

2. Olá! 🇧🇷
I am Klaus Laube
In ❤ with Django since version 0.96
Back-end developer at Son of a Tailor
klauslaube.com.br
github.com/kplaube

3. What’s an API again?

4. “(...) a set of dedicated URLs that return pure
data responses — meaning the responses
won’t contain the kind of presentational
overhead that you would expect in a
graphical user interface like a website.
Petr Gazarov
https://www.freecodecamp.org/news/what-is-an-api-in-english-please-b880a3214a82/

5. Let's build a
product! 🚀

6. The Code-First approach
Install Django
It’s not up to decision
picking a different
framework ❤

7. The Code-First approach
Install Django
It’s not up to decision
picking a different
framework ❤
Design the
database
Come up with
diagrams, define the
indexes, describe
relationships 💾

8. The Code-First approach
Install Django
It’s not up to decision
picking a different
framework ❤
Design the
database
Come up with
diagrams, define the
indexes, describe
relationships 💾
Write the code
Organize the packages,
do some TDD, write the
models, the views,
perhaps some API 👨‍💻

9. The Code-First approach
Install Django
It’s not up to decision
picking a different
framework ❤
Design the
database
Come up with
diagrams, define the
indexes, describe
relationships 💾
Write the code
Organize the packages,
do some TDD, write the
models, the views,
perhaps some API 👨‍💻
Deploy &
release
Deal with CI, CD, PaaS,
provisioning,
monitoring, caching,
etc 🖥

10. The Code-First approach
Install Django
It’s not up to decision
picking a different
framework ❤
Design the
database
Come up with
diagrams, define the
indexes, describe
relationships 💾
Write the code
Organize the packages,
do some TDD, write the
models, the views,
perhaps some API 👨‍💻
Expose
Let other stakeholders
know about your
release 🎉
☝
Here is where we’ll
start to integrate with
other developers
Deploy &
release
Deal with CI, CD, PaaS,
provisioning,
monitoring, caching,
etc 🖥

11. “Today Django is arguably used more often as
just a back-end API rather than a full
monolithic website solution at large
companies!
William S. Vincent
Django for APIs

12. What’s API-First?

13. “(...) the first, most waterfall aspect of
application development is the design of the
API’s.
Casey Lutz
https://medium.com/trimble-maps-engineering-blog/api-first-development-and-openapi-83
5afb46b7f1

14. 3 principles of
API-First Design

15. #1
Your API is the first user interface of your application

16. #2
Your API comes first, then the implementation

17. #3
Your API is described (and maybe even self-descriptive)

18. It’s about caring for other
developers! 👨‍💻 👩‍💻

19. How can we do
that with
Django? 🤔

20. Design the API
Understand the
requirements, know your
stakeholders, set standards,
start defining behaviours.
API Blueprint example 👉
20

21. Validate
Get stakeholders involved,
think about use cases,
validate ideas through mock
servers, and get an
agreement.
Or you can use Prism:
https://stoplight.io/open-source/pris
m/
21

22. Test! Test! Test!
https://dredd.org

23. Implement
It’s time for some coding.
And it’s not just you! With a
solid contract your
stakeholders can start the
development as well.
Django REST Framework example 👉
23

24. What about {over,under}-fetching?
https://github.com/rsinger86/drf-flex-fields

25. Or consider
GraphQL 🤷‍♂

26. It’s official!
It’s time to turn the
agreement into a
specification.
rest_framework (with
uritemplate and pyyaml) is
enough to do this job.
26
$ python manage.py generateschema >
openapi-schema.yml

27. How to deal with changes?
▷ Path: mytodoapp.com/v1/tasks
▷ Querystring: mytodoapp.com/tasks?version=1.0
▷ Host: v1.mytodoapp.com/tasks
▷ Accept header: Accept: application/json; version=1.0
▷ Custom header: X-API-VERSION
▷ No versioning at all 🙃
https://www.django-rest-framework.org/api-guide/versioning/

28. Release
Turn the specification public.
Publish the API
documentation. drf-yasg is
your sidekick here.

29. Engage
Promote your API, start
monitoring, collect feedback,
and learn from your mistakes
and successes.
29

30. Repeat ♻

31. Further readings:
API-First Processes
and Tools
bit.ly/api-first-article
31

32. Further readings:
How To Design
Great APIs With
API-First Design
bit.ly/3hQYw7d
32

33. Further readings:
Django for APIs
leanpub.com/djangoforapis
33

34. Tak! 🇩🇰
You can find me at:
klauslaube.com.br
github.com/kplaube
Django Forum: kplaube