django class based views for beginners
TRANSCRIPT
Django Class-based Viewsfor Beginners
Spin Lai
Function-based View
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)
Function-based View
View Functions
Function-based View
View Functions
Function-based View
How does it work?
Request
Django FBV
post_list() Response
Class-based View
Class-based View
What is Class-based View?
▸ Django views based on class
▸ Actually called as Function
▸ Using mixins to add functionality
Class-based View
What does it look like?
Class-based View
How does it work?
Request
Django CBV
as_view()
dispatch()
get() / post() / put() …
Response
Mixins
Mixins
Image source : http://atwinkyaday.blogspot.tw/2012_12_01_archive.html
Mixins
Flavour
Image source : http://thebakingbird.com/ice-cream/humphry-slocombe-the-hipster-ice-cream-parlor-of-ice-cream-parlors/
Mixins
+Flavour
Mix-insImage source : http://coldstoneofaberdeen.com/ice-cream/mix-go/
Mixins
+ =Flavour
Mix-insImage source : http://www.thecomfortofcooking.com/2014/04/amazing-no-churn-ice-cream-6-flavors.html
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
Mixins
Why?
▸ Adding functionality to classes
▸ Improve modularity
Mixins
When to use?
▸ Reuse code / features across multiple classes
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
Mixins - Rule of thumb
Base view classes provided by Django always go to the right
Mixins - Rule of thumb
Mixins go to the left of the base view
Mixins - Rule of thumb
Mixins should inherit from Python’s built-in object type
Built-in Class-based Generic Views
Built-in Class-based Generic Views
Category of Built-in Class-based Generic Views
▸ Base
▸ List
▸ Detail
▸ Edit
Built-in Class-based Generic Views
Base Generic Views
▸ django.views.generic.View
▸ django.views.generic.TemplateView
▸ django.views.generic.RedirectView
Built-in Class-based Generic Views
List Generic Views
▸ django.views.generic.list.ListView
Built-in Class-based Generic Views
Detail Generic Views
▸ django.views.generic.detail.DetailView
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
Usage of CBVs
Usage of CBVs
TemplateView
Usage of CBVs
ListView
Usage of CBVs
CreateView
CBVs and Mixins
CBVs and Mixins
TemplateView
TemplateView
View ContextMixin TemplateResponseMixin
CBVs and Mixins
ListView
ListView
View TemplateResponseMixin
ContextMixin
MultipleObjectMixin
BaseListView MutipleObjectTemplateResponseMixin
CBVs and Mixins
DetailView
DetailView
View TemplateResponseMixin
ContextMixin
SingleObjectMixin
BaseDetailView SingleObjectTemplateResponseMixin
CBVs and Mixins
FormView
FormView
ProcessFormView
TemplateResponseMixin
ContextMixin
FormMixin
BaseFormView
View
The Dark Side
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
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”
Demo
Takeaways
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?
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
Resources
Resources
Links
▸ https://docs.djangoproject.com/ja/1.9/topics/class-based-views/
▸ https://ccbv.co.uk/
▸ http://django-vanilla-views.org/
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
Thank you