Django Class-based Views for Beginners

An introduction of Django class-based views for beginners

Transcript

1. Django Class-based Views for Beginners Spin Lai
2. Function-based View
3. Function-based View What is Function-based View? ▸ A Django views is a function that : ▸ Take an HTTP request as the input ▸ Turn it into a HTTP response ▸ a.k.a Function-based Views (FBVs)
4. Function-based View View Functions
5. Function-based View View Functions
6. Function-based View How does it work? Request Django FBV post_list() Response
7. Class-based View
8. Class-based View What is Class-based View? ▸ Django views based on class ▸ Actually called as Function ▸ Using mixins to add functionality
9. Class-based View What does it look like?
10. Class-based View How does it work? Request Django CBV as_view() dispatch() get() / post() / put() … Response
11. Mixins
12. Mixins Image source : http://atwinkyaday.blogspot.tw/2012_12_01_archive.html
13. Mixins Flavour Image source : http://thebakingbird.com/ice-cream/humphry-slocombe-the-hipster-ice-cream-parlor-of-ice-cream-parlors/
14. Mixins + Flavour Mix-ins Image source : http://coldstoneofaberdeen.com/ice-cream/mix-go/
15. Mixins + = Flavour Mix-ins Image source : http://www.thecomfortofcooking.com/2014/04/amazing-no-churn-ice-cream-6-flavors.html
16. Mixins What is Mixin in Python? ▸ Actually, mixins are ordinary Python classes ▸ Provides functionality to be inherited ▸ But isn’t meant to be instantiated on its own
17. Mixins Why? ▸ Adding functionality to classes ▸ Improve modularity
18. Mixins When to use? ▸ Reuse code / features across multiple classes
19. Mixins Rule of thumb ▸ Base view classes provided by Django always go to the right. ▸ Mixins go to the left of the base view. ▸ Mixins should inherit from Python’s built-in object type ▸ Keep shallow inheritance chain
20. Mixins - Rule of thumb Base view classes provided by Django always go to the right
21. Mixins - Rule of thumb Mixins go to the left of the base view
22. Mixins - Rule of thumb Mixins should inherit from Python’s built-in object type
23. Built-in Class-based Generic Views
24. Built-in Class-based Generic Views Category of Built-in Class-based Generic Views ▸ Base ▸ List ▸ Detail ▸ Edit
25. Built-in Class-based Generic Views Base Generic Views ▸ django.views.generic.View ▸ django.views.generic.TemplateView ▸ django.views.generic.RedirectView
26. Built-in Class-based Generic Views List Generic Views ▸ django.views.generic.list.ListView
27. Built-in Class-based Generic Views Detail Generic Views ▸ django.views.generic.detail.DetailView
28. Built-in Class-based Generic Views Edit Generic Views ▸ django.views.generic.FormView ▸ django.views.generic.CreateView ▸ django.views.generic.UpdateView ▸ django.views.generic.DeleteView
29. Usage of CBVs
30. Usage of CBVs TemplateView
31. Usage of CBVs ListView
32. Usage of CBVs CreateView
33. CBVs and Mixins
34. CBVs and Mixins TemplateView TemplateView View ContextMixin TemplateResponseMixin
35. CBVs and Mixins ListView ListView View TemplateResponseMixin ContextMixin MultipleObjectMixin BaseListView MutipleObjectTemplateResponseMixin
36. CBVs and Mixins DetailView DetailView View TemplateResponseMixin ContextMixin SingleObjectMixin BaseDetailView SingleObjectTemplateResponseMixin
37. CBVs and Mixins FormView FormView ProcessFormView TemplateResponseMixin ContextMixin FormMixin BaseFormView View
38. The Dark Side
39. The Dark Side The Dark Side of Mixins ▸ Easy to lose track of the origin of your methods ▸ You may actually polluting the class namespace
40. The Dark Side The Dark Side of Generic CBVs ▸ Flow control is totally hidden ▸ The order of execution may not be obvious to anyone else ▸ More difficult to debug ▸ To understand what’s going on. You have to read the API docs, or even the source code of CBVs … ▸ Remember? “Explicit is better than implicit”
41. Demo
42. Takeaways
43. Takeaways FBVs or CBVs ? ▸ Does the Generic CBVs closely match what you need? ▸ Can you use a CBV just by overriding some attributes? ▸ Do you need to subclass your views to create some views?
44. Takeaways Guidelines ▸ Keep your view simple ▸ Never repeat code in your views ▸ Only handle presentation logic in views ▸ Keep your mixins simpler ▸ Don’t use CBVs to write 403, 404… error handlers. Use FBVs instead
45. Resources
46. Resources Links ▸ https://docs.djangoproject.com/ja/1.9/topics/class-based- views/ ▸ https://ccbv.co.uk/ ▸ http://django-vanilla-views.org/
47. Resources Books ▸ 「Two Scoops of Django: Best Practices for Django 1.8」 ▸ Chap 8 Function-and-Class-Based Views ▸ Chap 9 Best Practices for Function-Based Views ▸ Chap 10 Best Practices for Class-Based Views
48. Thank you