Models
4 snippetsDjango ORM model definitions
Basic Model
from django.db import models
class Post(models.Model):
title = models.CharField(max_length=200)
body = models.TextField()
published = models.BooleanField(default=False)
created_at = models.DateTimeField(auto_now_add=True)
class Meta:
ordering = ['-created_at']Relationships
class Comment(models.Model):
post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name='comments')
author = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
tags = models.ManyToManyField(Tag, blank=True)Manager
class PublishedManager(models.Manager):
def get_queryset(self):
return super().get_queryset().filter(published=True)
class Post(models.Model):
objects = models.Manager()
published = PublishedManager()Migrations
python manage.py makemigrations
python manage.py migrate
python manage.py showmigrations
python manage.py sqlmigrate app_name 0001Views
3 snippetsFunction and class-based views
Function View
from django.shortcuts import render, get_object_or_404
def post_detail(request, pk):
post = get_object_or_404(Post, pk=pk)
return render(request, 'posts/detail.html', {'post': post})Class-Based View
from django.views.generic import ListView, DetailView, CreateView
class PostList(ListView):
model = Post
template_name = 'posts/list.html'
context_object_name = 'posts'
paginate_by = 10CreateView
class PostCreate(CreateView):
model = Post
fields = ['title', 'body']
success_url = reverse_lazy('post-list')
def form_valid(self, form):
form.instance.author = self.request.user
return super().form_valid(form)URLs
2 snippetsURL routing patterns
URL Patterns
from django.urls import path, include
urlpatterns = [
path('', views.index, name='index'),
path('posts/<int:pk>/', views.post_detail, name='post-detail'),
path('posts/<slug:slug>/', views.post_by_slug),
path('api/', include('api.urls')),
]Reverse URL
from django.urls import reverse
url = reverse('post-detail', args=[42])
# In template: {% url 'post-detail' post.pk %}Tired of looking up syntax?
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QuerySets
4 snippetsDatabase queries with Django ORM
Filter & Exclude
Post.objects.filter(published=True)
Post.objects.filter(title__icontains='django')
Post.objects.exclude(author=None)
Post.objects.filter(created_at__year=2026)Q Objects
from django.db.models import Q
Post.objects.filter(
Q(title__contains='django') | Q(body__contains='django'),
published=True
)Annotate & Aggregate
from django.db.models import Count, Avg, F
Post.objects.annotate(comment_count=Count('comments'))
Post.objects.aggregate(avg_score=Avg('score'))
Post.objects.filter(views__gt=F('likes') * 2)Select Related
# ForeignKey (single query JOIN)
Post.objects.select_related('author')
# ManyToMany (separate query, prefetched)
Post.objects.prefetch_related('tags', 'comments')Templates
3 snippetsDjango template language
Variables & Filters
{{ post.title }}
{{ post.title|truncatewords:30 }}
{{ post.created_at|date:"M d, Y" }}
{{ items|length }}
{{ text|linebreaks }}Tags
{% if post.published %}
<h1>{{ post.title }}</h1>
{% endif %}
{% for post in posts %}
<li>{{ forloop.counter }}. {{ post.title }}</li>
{% empty %}
<li>No posts yet.</li>
{% endfor %}Inheritance
{# base.html #}
<html>
<body>{% block content %}{% endblock %}</body>
</html>
{# page.html #}
{% extends "base.html" %}
{% block content %}<h1>Hello</h1>{% endblock %}Forms
3 snippetsForm handling and validation
ModelForm
from django import forms
class PostForm(forms.ModelForm):
class Meta:
model = Post
fields = ['title', 'body']
widgets = {'body': forms.Textarea(attrs={'rows': 5})}Validation
class PostForm(forms.ModelForm):
def clean_title(self):
title = self.cleaned_data['title']
if len(title) < 5:
raise forms.ValidationError('Title too short')
return titleView Integration
def create_post(request):
form = PostForm(request.POST or None)
if form.is_valid():
post = form.save(commit=False)
post.author = request.user
post.save()
return redirect('post-detail', pk=post.pk)
return render(request, 'posts/form.html', {'form': form})