API-Driven Django

A tutorial on making API-Driven Django apps.

Transcript

1. API-Driven Django Philip James PyCon 2018 @phildini
2. Who am I?
3. Format • Buddy system • Switching pairs • SHcky Notes • Learn by trying first • You can get this all at the end
4. Some Pairing Best PracHces • Less familiar person should type first • Switching pairs at different sessions • One machine, one set of hands • No grabbing the keyboard
5. Goals • Build a working Django API-First App for collecHng civic government data • Have that App use the same code for API endpoints as well as rendered templates • Have that app let anyone read, but only authorized users write
6. https://www.djangoproject.com/
7. http://www.django-rest-framework.org/
8. CivicAPI • Django app to track votes taken at civic government meeHngs • Needs to support rich frontends and API clients • CRUD app on votes taken
9. Create Retrieve Update Destroy
10. GeXng started
11. Pipenv https://docs.pipenv.org/ GeXng started
12. mkdir civicapi && cd civicapi pipenv --three install django GeXng started
13. pipenv run vs. pipenv shell GeXng started
14. pipenv shell django-admin.py startproject civicapi . GeXng started
15. django-admin.py startapp votes GeXng started
16. python manage.py migrate GeXng started
17. python manage.py createsuperuser GeXng started
18. python manage.py runserver GeXng started
19. {Check data in admin}
20. •subject: string, required •vote_taken: date and Hme, required •ayes: integer, not required •nays: integer, not required Vote Model https://docs.djangoproject.com/en/2.0/ref/models/fields/ google: django model field reference
21. Pair Exercise - 10 min 1. Make sure reqs are installed and project is set up 2. Try to build the model in votes/models.py 3. Add votes to installed_apps in civicapi/seXngs.py 4. python manage.py migrate 5. (extra - see it in admin) https://docs.djangoproject.com/en/2.0/ref/models/fields/ google: django model field reference
22. {Show Code}
23. Views
24. Django Generic Views?
25. To create: • View that lists and creates Votes We need: 1. django.views.generic.list.ListView 2. django.views.generic.edit.CreateView 3. Template file 4. URL update 5. (Possibly) a ModelForm
26. What about an API?
27. Two op&ons: 1. Add separate API views 2. Munge JSON responses into exisHng views
28. What’s beker for the client? What’s beker for the dev?
29. Rich frontends, client-first == API-Driven, API First
30. StarHng with
31. To create: • APIView that lists and creates Votes We need: 1. ModelSerializer for Vote 2. rest_framework.generics.ListCreateAPIView
32. DRF ModelSerializers http://www.django-rest-framework.org/api-guide/serializers/#modelserializer
33. DRF ModelSerializers class AccountSerializer(serializers.ModelSerializer): class Meta: model = Account fields = ('id', 'account_name', 'users', 'created') http://www.django-rest-framework.org/api-guide/serializers/#modelserializer
34. Pair Exercise - 10 min 1. pipenv install djangorestframework 2. add rest_framework to the Django app 3. Try to make the ModelSerializer for Vote in the votes app 4. write a test to verify the serialized data http://www.django-rest-framework.org/api-guide/serializers/#modelserializer
35. {Show Code}
36. DRF ListCreateAPIView
37. DRF ListCreateAPIView class UserList(generics.ListCreateAPIView): queryset = User.objects.all() serializer_class = UserSerializer
38. Pair Exercise - 10 min 1. add a VoteList ListCreateAPIView to views 2. add the view to urls.py at /votes/ 3. python manage.py runserver 4. open a browser, browse to localhost:8000 5. play around, try to create some votes 6. (opHonal: write a test for the view) http://www.django-rest-framework.org/api-guide/generic-views/#examples
39. {Show Code}
40. DRF Renderers
41. DRF JSONRenderer OrderedDict([('count', 3), ('next', None), ('previous', None), ('results', [OrderedDict([('id', 1), ('subject', 'More apps should be built in Django!'), ('vote_taken', '2018-04-14T19:51:09Z'), ('ayes', 100), ('nays', 0)]),…])]) {'count': 3, 'next': None, 'previous': None, 'results': [{'id': 1, 'subject': 'More apps should be built in Django!', 'vote_taken': '2018-04-14T19:51:09Z', 'ayes': 100, 'nays': 0},...]}
42. DRF TemplateHTMLRenderer OrderedDict([('count', 3), ('next', None), ('previous', None), ('results', [OrderedDict([('id', 1), ('subject', 'More apps should be built in Django!'), ('vote_taken', '2018-04-14T19:51:09Z'), ('ayes', 100), ('nays', 0)]),…])]) <ul> <li><a href=“/votes/1/"> More apps should be built in Django! - 100/0 on 2018-04-14T19:51:09Z </a></li> … </ul>
43. DRF BrowsableAPIRenderer OrderedDict([('count', 3), ('next', None), ('previous', None), ('results', [OrderedDict([('id', 1), ('subject', 'More apps should be built in Django!'), ('vote_taken', '2018-04-14T19:51:09Z'), ('ayes', 100), ('nays', 0)]),…])])
44. Django TemplaHng <ul> {% for user in results %} <li><a href="/users/{{ user.id }}/">{{ user.name }}</a></li> {% endfor %} </ul>
45. DRF Template Gotcha! In se,ngs.py: REST_FRAMEWORK = { 'DEFAULT_PAGINATION_CLASS': 'rest_framework.paginaHon.PageNumberPaginaHon', 'PAGE_SIZE': 10, }
46. Pair Exercise - 20 min 1. add a templates directory to votes 2. add a vote_list.html template 3. add the TemplateHTMLRenderer to VoteList’s renderer_classes, along with JSONRenderer and BrowsableAPIRenderer 4. point the template_name to “vote_list.html" 5. Create votes/templates/vote_list.html 6. Browse to /votes/ and see the list. http://www.django-rest-framework.org/api-guide/renderers/#templatehtmlrenderer
47. {Show Code}
48. Tip! ?format=
49. Break!
50. Why not use the BrowseableAPIRenderer for everything?
51. CreaHng a Vote with the rendered template
52. CreaHng a Vote with the rendered template <form action="/votes/" method="POST" enctype="multipart/form-data"> {% csrf_token %} <p> <label for="subject">Subject</label> <input id="subject" name="subject" type="text"> </p> <p> <label for="vote_taken">Vote taken</label> <input id="vote_taken" name="vote_taken" type="datetime-local"> </p> <p> <label for="ayes">Ayes</label> <input id="ayes" name="ayes" type="number"> </p> <p> <label for="nays">Nays</label> <input id="nays" name="nays" type="number"> </p> <input type="submit" value="Save"> </form>
53. CreaHng a Vote with the rendered template def create(self, request, *args, **kwargs): response = super(VoteList, self).create(request, *args, **kwargs) if request.accepted_renderer.format == 'html' and response.status_code == 201: return redirect('/votes/') return response
54. Pair Exercise - 5 min 1. add the code snippets to vote_list.html and views.py 2. Browse to /votes/ and add a vote via the interface.
55. {Review Code}
56. Vote Detail
57. DRF RetrieveUpdateDestroyAPIView class UserDetail(generics.RetrieveUpdateDestroyAPIView): queryset = User.objects.all() serializer_class = UserSerializer
58. Pair Exercise - 10 min 1. add a VoteDetail view, using generics.RetrieveUpdateDestroyAPIView 2. Don’t forget the right renderers! 3. add that view to urls.py 4. add a vote.html template 5. point the template_name to “vote.html" 6. Wire up the links in “vote_list.html” 7. Browse to /votes/ and see the list, make sure the links are clickable. http://www.django-rest-framework.org/tutorial/3-class-based-views/#using-generic-class- based-views
59. {Show Code}
60. AuthenHcaHon
61. Reading vs. WriHng
62. Session, Token, OAuth
63. DRF AuthenHcaHon Classes && DRF Permissions Classes
64. Pair Exercise - 10 min 1. add permissions.IsAuthenHcatedOrReadOnly to VoteList view and VoteDetail view 2. Browse to /votes/ try adding a vote 3. Open an anonymous browser window, try doing the same thing 4. (opHonal: add some tests for the authed and non- authed requests) http://www.django-rest-framework.org/tutorial/4-authentication-and-permissions/#adding- required-permissions-to-views
65. {Show Code}
66. Keeping things DRY
67. Keeping things DRY •We can use mixins for common funcHonality •Capture auth, permissions, renderers in one place •While we’re here, only allow the BrowseableAPIRenderer to staff users
68. def get_renderers(self): renderer_classes = self.renderer_classes if self.request.user.is_staff: renderer_classes += [BrowsableAPIRenderer] return [renderer() for renderer in renderer_classes]
69. Pair Exercise - 10 min 1. add a VoteAPIMixin that captures renderer classes, queryset, serializer_class, and permission classes 2. Make sure the get_renderers snippet is defined in the mixin 3. Add the mixin to both view classes, remove the duplicate code from the views 4. Browse the api and make sure things sHll work. 5. Run tests and make sure things sHll work
70. {Show Code}
71. Token Auth
72. Pair Exercise - 10 min 1. add ‘rest_framework.authtoken' to seXngs.py 2. Add correct authenHcaHon classes to seXngs.py ‘DEFAULT_AUTHENTICATION_CLASSES': ( 'rest_framework.authentication.BasicAuthentication', 'rest_framework.authentication.SessionAuthentication', 'rest_framework.authentication.TokenAuthentication', ) http://www.django-rest-framework.org/api-guide/authentication/#tokenauthentication
73. TesHng
74. TesHng • http://www.django-rest-framework.org/ api-guide/testing/ • https://docs.djangoproject.com/en/2.0/ topics/testing/ •“Code without tests is broken as designed.” - Jacob Kaplan-Moss
75. Pair Exercise - 10 min 1. Add more tests for VoteList and VoteDetail views 2. Pay special akenHon to edge cases with authenHcaHon and renderer type 3. Any more tests you can think of? 4. (opHonal: add ability to edit votes from VoteDetail)
76. Where to go from here?
77. Deploying OAuth Django Channels Working with Web Frontends
78. Thanks! Philip James phildini@phildini.net @phildini@wandering.shop https://github.com/phildini/api-driven-django