Django Cheatsheet

Project

To create a blank new project:

django-admin startproject mysite

To apply changes of a database:

python manage.py migrate

To start the dev server:

python manage.py runserver

If you want to run it on a specific port try:

python manage.py runserver 127.0.0.1:<port>

Project Structure

• manage.py : command-line utility.
• mysite/ : project folder.
  • asgi.py : ASGI configuration (Asynchronous Web Server & App).
  • settings.py : project configuration.
  • urls.py : file to define your urls.
  • wsgi.py: WSGI configuration (Web Server Gateway Interface).

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Apps

To create a new app

python manage.py startapp <appName>

You will need a model to design you app data schema. In every Django App, you have a file named models.py where you can create the models defining python classes. Each class represents a db table and its attributes are the fields of the table. Model Field Reference

App Structure

• admin.py : register models for django admin.
• app.py : main config of the app.
• migrations/ : contains databases migrations.
• models.py : data models of the app.
• tests.py : app tests.
• views.py : has the logic of the app.

When you change a model you need to run the django migrations system that propagates the changes to the database tables:

python manage.py makemigrations <app>

And then sync the project with the new model:

python manage.py migrate

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SuperUser

Django has a built-in administration interface that can be usefull to see the data and edit it. To create a superuser:

python manage.py createsuperuser

To add a model to your administration site, you’ll have to edit admin.py file of your app:

from django.contrib import admin
from .models import <model>

admin.site.register(<model>)

You can customize this interface to display the data as you want. Django Admin Customization

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QuerySets and managers

You can define the database you are using in settings.py.

• Creating data - save()
• Getting data - get()
• Retrieving all objects - all()
• Retrieving filtered data - filter() or exclude()
• Ordering data - order_by()
• Deleting objects - delete()

Managers

The default manager is objects but you can define alternative managers to directly retrieve filtered data. Let’s see an example of a blog application manager:

class PublishedManager (models.Manager):
	def get_queryset(self):
		return super(PublishedManager, self).get_queryset().filter(status='published')

class Post(models.Model):
	# ...
	objects = models.Manager() # default manager (if you dont define it, it won't be created when you have custom managers)
	published = PublishedManager() # custom manager

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Building List and detail views

Create a view inside of your app directory on views.py. Let’s use again the blog site example:

from django.shortcuts import render, get_object_or_404
from .models import Post

def post_list (request):
	posts = Post.published.all() # we're using the custom manager ;)
	return render(request, 'blog/post/list.html', {'posts' : posts})

def post_detail (request, year, month, day, post):
	post = get_object_or_404(Post, slug=post, ...)
	return render (request, 'blog/post/detail.html', {'posts': posts})

Adding URL patterns for each view

You can create custom URL patterns for your apps by defining them in urls.py inside your app directory. Using the blog site it would look like this:

from django.urls import path
from . import views
app_name = 'blog'

urlpatterns = [
	# post views
	path('', views.post_list, name='post_list'),
	path('<int:year>/<int:month>/<int/day>/<slug:post>/',
			views.post_detail,
			name='post_detail'),
]