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Fixed 19385 -- Added ORM support for multicolumn joins 

This patch iproved two major parts in Django. First, the fields.related
was refactored. The main addition there was ForeignObject. Second, the
ORM now handles multicolumn joins in most cases, though there are still
cases that do not work correcly (split_exclude() for example).

In addition there were extesive changes to how GenericRelation works.
Before it was a fake m2m field, now it is a pure virtual fields and is
based on ForeignObject.

There is still much room for improvement. The related fields code is
still somewhat confusing, and how fields are represented in model._meta
should also be revisited.

This patch was written mostly by Jeremy Tillman with some final polish
by the committer.
This commit is contained in:
Anssi Kääriäinen 2013-03-24 18:08:01 +02:00
parent bc35b95274
commit 266de5f9ae
3 changed files with 490 additions and 0 deletions
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0
tests/foreign_object/__init__.py Normal file
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152
tests/foreign_object/models.py Normal file
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import datetime
from django.db import models
from django.db.models.fields.related import ReverseSingleRelatedObjectDescriptor
from django.utils.encoding import python_2_unicode_compatible
from django.utils.translation import get_language
class Country(models.Model):
# Table Column Fields
name = models.CharField(max_length=50)
def __unicode__(self):
return self.name
class Person(models.Model):
# Table Column Fields
name = models.CharField(max_length=128)
person_country_id = models.IntegerField()
# Relation Fields
person_country = models.ForeignObject(
Country, from_fields=['person_country_id'], to_fields=['id'])
friends = models.ManyToManyField('self', through='Friendship', symmetrical=False)
class Meta:
ordering = ('name',)
def __unicode__(self):
return self.name
class Group(models.Model):
# Table Column Fields
name = models.CharField(max_length=128)
group_country = models.ForeignKey(Country)
members = models.ManyToManyField(Person, related_name='groups', through='Membership')
class Meta:
ordering = ('name',)
def __unicode__(self):
return self.name
class Membership(models.Model):
# Table Column Fields
membership_country = models.ForeignKey(Country)
date_joined = models.DateTimeField(default=datetime.datetime.now)
invite_reason = models.CharField(max_length=64, null=True)
person_id = models.IntegerField()
group_id = models.IntegerField()
# Relation Fields
person = models.ForeignObject(Person,
from_fields=['membership_country', 'person_id'],
to_fields=['person_country_id', 'id'])
group = models.ForeignObject(Group,
from_fields=['membership_country', 'group_id'],
to_fields=['group_country', 'id'])
class Meta:
ordering = ('date_joined', 'invite_reason')
def __unicode__(self):
return "%s is a member of %s" % (self.person.name, self.group.name)
class Friendship(models.Model):
# Table Column Fields
from_friend_country = models.ForeignKey(Country, related_name="from_friend_country")
from_friend_id = models.IntegerField()
to_friend_country_id = models.IntegerField()
to_friend_id = models.IntegerField()
# Relation Fields
from_friend = models.ForeignObject(Person,
from_fields=['from_friend_country', 'from_friend_id'],
to_fields=['person_country_id', 'id'],
related_name='from_friend')
to_friend_country = models.ForeignObject(Country,
from_fields=['to_friend_country_id'],
to_fields=['id'],
related_name='to_friend_country')
to_friend = models.ForeignObject(Person,
from_fields=['to_friend_country_id', 'to_friend_id'],
to_fields=['person_country_id', 'id'],
related_name='to_friend')
class ArticleTranslationDescriptor(ReverseSingleRelatedObjectDescriptor):
"""
The set of articletranslation should not set any local fields.
"""
def __set__(self, instance, value):
if instance is None:
raise AttributeError("%s must be accessed via instance" % self.field.name)
setattr(instance, self.cache_name, value)
if value is not None and not self.field.rel.multiple:
setattr(value, self.field.related.get_cache_name(), instance)
class ColConstraint(object):
# Antyhing with as_sql() method works in get_extra_restriction().
def __init__(self, alias, col, value):
self.alias, self.col, self.value = alias, col, value
def as_sql(self, qn, connection):
return '%s.%s = %%s' % (qn(self.alias), qn(self.col)), [self.value]
class ActiveTranslationField(models.ForeignObject):
"""
This field will allow querying and fetching the currently active translation
for Article from ArticleTranslation.
"""
requires_unique_target = False
def get_extra_restriction(self, where_class, alias, related_alias):
return ColConstraint(alias, 'lang', get_language())
def get_extra_descriptor_filter(self):
return {'lang': get_language()}
def contribute_to_class(self, cls, name):
super(ActiveTranslationField, self).contribute_to_class(cls, name)
setattr(cls, self.name, ArticleTranslationDescriptor(self))
@python_2_unicode_compatible
class Article(models.Model):
active_translation = ActiveTranslationField(
'ArticleTranslation',
from_fields=['id'],
to_fields=['article'],
related_name='+',
null=True)
pub_date = models.DateField()
def __str__(self):
try:
return self.active_translation.title
except ArticleTranslation.DoesNotExist:
return '[No translation found]'
class ArticleTranslation(models.Model):
article = models.ForeignKey(Article)
lang = models.CharField(max_length='2')
title = models.CharField(max_length=100)
body = models.TextField()
abstract = models.CharField(max_length=400, null=True)
class Meta:
unique_together = ('article', 'lang')
ordering = ('active_translation__title',)

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tests/foreign_object/tests.py Normal file
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import datetime
from operator import attrgetter
from .models import Country, Person, Group, Membership, Friendship, Article, ArticleTranslation
from django.test import TestCase
from django.utils.translation import activate
from django import forms
class MultiColumnFKTests(TestCase):
def setUp(self):
# Creating countries
self.usa = Country.objects.create(name="United States of America")
self.soviet_union = Country.objects.create(name="Soviet Union")
Person()
# Creating People
self.bob = Person()
self.bob.name = 'Bob'
self.bob.person_country = self.usa
self.bob.save()
self.jim = Person.objects.create(name='Jim', person_country=self.usa)
self.george = Person.objects.create(name='George', person_country=self.usa)
self.jane = Person.objects.create(name='Jane', person_country=self.soviet_union)
self.mark = Person.objects.create(name='Mark', person_country=self.soviet_union)
self.sam = Person.objects.create(name='Sam', person_country=self.soviet_union)
# Creating Groups
self.kgb = Group.objects.create(name='KGB', group_country=self.soviet_union)
self.cia = Group.objects.create(name='CIA', group_country=self.usa)
self.republican = Group.objects.create(name='Republican', group_country=self.usa)
self.democrat = Group.objects.create(name='Democrat', group_country=self.usa)
def test_get_succeeds_on_multicolumn_match(self):
# Membership objects have access to their related Person if both
# country_ids match between them
membership = Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.bob.id, group_id=self.cia.id)
person = membership.person
self.assertEqual((person.id, person.name), (self.bob.id, "Bob"))
def test_get_fails_on_multicolumn_mismatch(self):
# Membership objects returns DoesNotExist error when the there is no
# Person with the same id and country_id
membership = Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.jane.id, group_id=self.cia.id)
self.assertRaises(Person.DoesNotExist, getattr, membership, 'person')
def test_reverse_query_returns_correct_result(self):
# Creating a valid membership because it has the same country has the person
Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.bob.id, group_id=self.cia.id)
# Creating an invalid membership because it has a different country has the person
Membership.objects.create(
membership_country_id=self.soviet_union.id, person_id=self.bob.id,
group_id=self.republican.id)
self.assertQuerysetEqual(
self.bob.membership_set.all(), [
self.cia.id
],
attrgetter("group_id")
)
def test_query_filters_correctly(self):
# Creating a to valid memberships
Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.bob.id, group_id=self.cia.id)
Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.jim.id,
group_id=self.cia.id)
# Creating an invalid membership
Membership.objects.create(membership_country_id=self.soviet_union.id,
person_id=self.george.id, group_id=self.cia.id)
self.assertQuerysetEqual(
Membership.objects.filter(person__name__contains='o'), [
self.bob.id
],
attrgetter("person_id")
)
def test_reverse_query_filters_correctly(self):
timemark = datetime.datetime.utcnow()
timedelta = datetime.timedelta(days=1)
# Creating a to valid memberships
Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.bob.id,
group_id=self.cia.id, date_joined=timemark - timedelta)
Membership.objects.create(
membership_country_id=self.usa.id, person_id=self.jim.id,
group_id=self.cia.id, date_joined=timemark + timedelta)
# Creating an invalid membership
Membership.objects.create(
membership_country_id=self.soviet_union.id, person_id=self.george.id,
group_id=self.cia.id, date_joined=timemark + timedelta)
self.assertQuerysetEqual(
Person.objects.filter(membership__date_joined__gte=timemark), [
'Jim'
],
attrgetter('name')
)
def test_forward_in_lookup_filters_correctly(self):
Membership.objects.create(membership_country_id=self.usa.id, person_id=self.bob.id,
group_id=self.cia.id)
Membership.objects.create(membership_country_id=self.usa.id, person_id=self.jim.id,
group_id=self.cia.id)
# Creating an invalid membership
Membership.objects.create(
membership_country_id=self.soviet_union.id, person_id=self.george.id,
group_id=self.cia.id)
self.assertQuerysetEqual(
Membership.objects.filter(person__in=[self.george, self.jim]), [
self.jim.id,
],
attrgetter('person_id')
)
self.assertQuerysetEqual(
Membership.objects.filter(person__in=Person.objects.filter(name='Jim')), [
self.jim.id,
],
attrgetter('person_id')
)
def test_select_related_foreignkey_forward_works(self):
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
with self.assertNumQueries(1):
people = [m.person for m in Membership.objects.select_related('person')]
normal_people = [m.person for m in Membership.objects.all()]
self.assertEqual(people, normal_people)
def test_prefetch_foreignkey_forward_works(self):
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
with self.assertNumQueries(2):
people = [m.person for m in Membership.objects.prefetch_related('person')]
normal_people = [m.person for m in Membership.objects.all()]
self.assertEqual(people, normal_people)
def test_prefetch_foreignkey_reverse_works(self):
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
with self.assertNumQueries(2):
membership_sets = [list(p.membership_set.all())
for p in Person.objects.prefetch_related('membership_set')]
normal_membership_sets = [list(p.membership_set.all()) for p in Person.objects.all()]
self.assertEqual(membership_sets, normal_membership_sets)
def test_m2m_through_forward_returns_valid_members(self):
# We start out by making sure that the Group 'CIA' has no members.
self.assertQuerysetEqual(
self.cia.members.all(),
[]
)
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.cia)
# Let's check to make sure that it worked. Bob and Jim should be members of the CIA.
self.assertQuerysetEqual(
self.cia.members.all(), [
'Bob',
'Jim'
], attrgetter("name")
)
def test_m2m_through_reverse_returns_valid_members(self):
# We start out by making sure that Bob is in no groups.
self.assertQuerysetEqual(
self.bob.groups.all(),
[]
)
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.bob,
group=self.republican)
# Bob should be in the CIA and a Republican
self.assertQuerysetEqual(
self.bob.groups.all(), [
'CIA',
'Republican'
], attrgetter("name")
)
def test_m2m_through_forward_ignores_invalid_members(self):
# We start out by making sure that the Group 'CIA' has no members.
self.assertQuerysetEqual(
self.cia.members.all(),
[]
)
# Something adds jane to group CIA but Jane is in Soviet Union which isn't CIA's country
Membership.objects.create(membership_country=self.usa, person=self.jane, group=self.cia)
# There should still be no members in CIA
self.assertQuerysetEqual(
self.cia.members.all(),
[]
)
def test_m2m_through_reverse_ignores_invalid_members(self):
# We start out by making sure that Jane has no groups.
self.assertQuerysetEqual(
self.jane.groups.all(),
[]
)
# Something adds jane to group CIA but Jane is in Soviet Union which isn't CIA's country
Membership.objects.create(membership_country=self.usa, person=self.jane, group=self.cia)
# Jane should still not be in any groups
self.assertQuerysetEqual(
self.jane.groups.all(),
[]
)
def test_m2m_through_on_self_works(self):
self.assertQuerysetEqual(
self.jane.friends.all(),
[]
)
Friendship.objects.create(
from_friend_country=self.jane.person_country, from_friend=self.jane,
to_friend_country=self.george.person_country, to_friend=self.george)
self.assertQuerysetEqual(
self.jane.friends.all(),
['George'], attrgetter("name")
)
def test_m2m_through_on_self_ignores_mismatch_columns(self):
self.assertQuerysetEqual(self.jane.friends.all(), [])
# Note that we use ids instead of instances. This is because instances on ForeignObject
# properties will set all related field off of the given instance
Friendship.objects.create(
from_friend_id=self.jane.id, to_friend_id=self.george.id,
to_friend_country_id=self.jane.person_country_id,
from_friend_country_id=self.george.person_country_id)
self.assertQuerysetEqual(self.jane.friends.all(), [])
def test_prefetch_related_m2m_foward_works(self):
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
with self.assertNumQueries(2):
members_lists = [list(g.members.all())
for g in Group.objects.prefetch_related('members')]
normal_members_lists = [list(g.members.all()) for g in Group.objects.all()]
self.assertEqual(members_lists, normal_members_lists)
def test_prefetch_related_m2m_reverse_works(self):
Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
with self.assertNumQueries(2):
groups_lists = [list(p.groups.all()) for p in Person.objects.prefetch_related('groups')]
normal_groups_lists = [list(p.groups.all()) for p in Person.objects.all()]
self.assertEqual(groups_lists, normal_groups_lists)
def test_translations(self):
activate('fi')
a1 = Article.objects.create(pub_date=datetime.date.today())
at1_fi = ArticleTranslation(article=a1, lang='fi', title='Otsikko', body='Diipadaapa')
at1_fi.save()
at2_en = ArticleTranslation(article=a1, lang='en', title='Title', body='Lalalalala')
at2_en.save()
with self.assertNumQueries(1):
fetched = Article.objects.select_related('active_translation').get(
active_translation__title='Otsikko')
self.assertTrue(fetched.active_translation.title == 'Otsikko')
a2 = Article.objects.create(pub_date=datetime.date.today())
at2_fi = ArticleTranslation(article=a2, lang='fi', title='Atsikko', body='Diipadaapa',
abstract='dipad')
at2_fi.save()
a3 = Article.objects.create(pub_date=datetime.date.today())
at3_en = ArticleTranslation(article=a3, lang='en', title='A title', body='lalalalala',
abstract='lala')
at3_en.save()
# Test model initialization with active_translation field.
a3 = Article(id=a3.id, pub_date=a3.pub_date, active_translation=at3_en)
a3.save()
self.assertEqual(
list(Article.objects.filter(active_translation__abstract=None)),
[a1, a3])
self.assertEqual(
list(Article.objects.filter(active_translation__abstract=None,
active_translation__pk__isnull=False)),
[a1])
activate('en')
self.assertEqual(
list(Article.objects.filter(active_translation__abstract=None)),
[a1, a2])
class FormsTests(TestCase):
# ForeignObjects should not have any form fields, currently the user needs
# to manually deal with the foreignobject relation.
class ArticleForm(forms.ModelForm):
class Meta:
model = Article
def test_foreign_object_form(self):
# A very crude test checking that the non-concrete fields do not get form fields.
form = FormsTests.ArticleForm()
self.assertIn('id_pub_date', form.as_table())
self.assertNotIn('active_translation', form.as_table())
form = FormsTests.ArticleForm(data={'pub_date': str(datetime.date.today())})
self.assertTrue(form.is_valid())
a = form.save()
self.assertEqual(a.pub_date, datetime.date.today())
form = FormsTests.ArticleForm(instance=a, data={'pub_date': '2013-01-01'})
a2 = form.save()
self.assertEqual(a.pk, a2.pk)
self.assertEqual(a2.pub_date, datetime.date(2013, 1, 1))