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March 19, 2015 16:43
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Clarification of behaviour of Django exclude() filters that span relationships
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from django.db import models | |
class Blog(models.Model): | |
name = models.CharField(max_length=100) | |
tagline = models.TextField() | |
def __unicode__(self): # __unicode__ on Python 2 | |
return self.name | |
class Author(models.Model): | |
name = models.CharField(max_length=50) | |
email = models.EmailField() | |
def __unicode__(self): # __unicode__ on Python 2 | |
return self.name | |
class Entry(models.Model): | |
blog = models.ForeignKey(Blog) | |
headline = models.CharField(max_length=255) | |
body_text = models.TextField() | |
pub_date = models.DateField() | |
mod_date = models.DateField(auto_now=True) | |
authors = models.ManyToManyField(Author) | |
n_comments = models.IntegerField(default=0) | |
n_pingbacks = models.IntegerField(default=0) | |
rating = models.IntegerField(default=0) | |
def __unicode__(self): # __unicode__ on Python 2 | |
return self.headline | |
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from datetime import date | |
from django.test import TestCase | |
from .models import Author, Blog, Entry | |
class Test(TestCase): | |
def test_queries(self): | |
Blog.objects.create(name='No entries') | |
neither = Blog.objects.create(name='Neither') | |
lennon = Blog.objects.create(name='Lennon') | |
published = Blog.objects.create(name='Published') | |
both_same_entry = Blog.objects.create(name='Both same') | |
both_different_entry = Blog.objects.create(name='Both different') | |
Entry.objects.create(headline='Foo', pub_date=date(2009, 1, 1), blog=neither) | |
Entry.objects.create(headline='Lennon', pub_date=date(2009, 6, 1), blog=lennon) | |
Entry.objects.create(headline='Published', pub_date=date(2008, 6, 1), blog=published) | |
Entry.objects.create(headline='Lennon', pub_date=date(2008, 1, 1), blog=both_same_entry) | |
Entry.objects.create(headline='Lennon', pub_date=date(2009, 1, 1), blog=both_different_entry) | |
Entry.objects.create(headline='Published', pub_date=date(2008, 1, 1), blog=both_different_entry) | |
# Exclude blogs that have BOTH: | |
# - entries published in 2008; AND | |
# - entries with "Lennon" in the headline | |
q1 = Blog.objects.exclude( | |
entry__headline__contains='Lennon', | |
entry__pub_date__year=2008, | |
).order_by('name') | |
self.assertQuerysetEqual(q1, ['<Blog: Lennon>', '<Blog: Neither>', '<Blog: No entries>', '<Blog: Published>']) | |
# Exclude blogs that have EITHER: | |
# - entries published in 2008; OR | |
# - entries with "Lennon" in the headline | |
q2 = Blog.objects.exclude( | |
entry__headline__contains='Lennon').exclude( | |
entry__pub_date__year=2008, | |
).order_by('name') | |
self.assertQuerysetEqual(q2, ['<Blog: Neither>', '<Blog: No entries>']) | |
# Exclude blogs that contain individual entries that are BOTH: | |
# - published in 2008; AND | |
# - have "Lennon" in the headline | |
q3 = Blog.objects.exclude( | |
entry=Entry.objects.filter( | |
headline__contains='Lennon', pub_date__year=2008, | |
).values('id'), | |
).order_by('name') | |
self.assertQuerysetEqual(q3, ['<Blog: Both different>', '<Blog: Lennon>', '<Blog: Neither>', '<Blog: No entries>', '<Blog: Published>']) |
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