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Fixed #19195 -- Allow explicit ordering by a relation _id
field.
Thanks to chrisedgemon for the report and shaib, akaariai and timgraham for the review.
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@ -464,8 +464,9 @@ class SQLCompiler(object):
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field, targets, alias, joins, path, opts = self._setup_joins(pieces, opts, alias)
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field, targets, alias, joins, path, opts = self._setup_joins(pieces, opts, alias)
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# If we get to this point and the field is a relation to another model,
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# If we get to this point and the field is a relation to another model,
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# append the default ordering for that model.
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# append the default ordering for that model unless the attribute name
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if field.rel and path and opts.ordering:
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# of the field is specified.
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if field.rel and path and opts.ordering and name != field.attname:
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# Firstly, avoid infinite loops.
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# Firstly, avoid infinite loops.
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if not already_seen:
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if not already_seen:
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already_seen = set()
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already_seen = set()
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@ -294,6 +294,18 @@ primary key if there is no :attr:`Meta.ordering
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...since the ``Blog`` model has no default ordering specified.
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...since the ``Blog`` model has no default ordering specified.
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.. versionadded:: 1.7
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Note that it is also possible to order a queryset by a related field,
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without incurring the cost of a JOIN, by referring to the ``_id`` of the
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related field::
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# No Join
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Entry.objects.order_by('blog_id')
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# Join
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Entry.objects.order_by('blog__id')
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Be cautious when ordering by fields in related models if you are also using
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Be cautious when ordering by fields in related models if you are also using
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:meth:`distinct()`. See the note in :meth:`distinct` for an explanation of how
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:meth:`distinct()`. See the note in :meth:`distinct` for an explanation of how
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related model ordering can change the expected results.
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related model ordering can change the expected results.
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@ -435,6 +447,21 @@ Examples (those after the first will only work on PostgreSQL)::
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>>> Entry.objects.order_by('author', 'pub_date').distinct('author')
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>>> Entry.objects.order_by('author', 'pub_date').distinct('author')
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[...]
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[...]
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.. note::
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Keep in mind that :meth:`order_by` uses any default related model ordering
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that has been defined. You might have to explicitly order by the relation
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``_id`` or referenced field to make sure the ``DISTINCT ON`` expressions
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match those at the beginning of the ``ORDER BY`` clause. For example, if
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the ``Blog`` model defined an :attr:`~django.db.models.Options.ordering` by
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``name``::
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Entry.objects.order_by('blog').distinct('blog')
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...wouldn't work because the query would be ordered by ``blog__name`` thus
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mismatching the ``DISTINCT ON`` expression. You'd have to explicitly order
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by the relation `_id` field (``blog_id`` in this case) or the referenced
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one (``blog__pk``) to make sure both expressions match.
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values
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values
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~~~~~~
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~~~~~~
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@ -702,6 +702,9 @@ Models
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Previously model field validation didn't prevent values out of their associated
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Previously model field validation didn't prevent values out of their associated
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column data type range from being saved resulting in an integrity error.
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column data type range from being saved resulting in an integrity error.
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* It is now possible to explicitly :meth:`~django.db.models.query.QuerySet.order_by`
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a relation ``_id`` field by using its attribute name.
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Signals
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Signals
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^^^^^^^
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^^^^^^^
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@ -17,8 +17,14 @@ from django.db import models
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from django.utils.encoding import python_2_unicode_compatible
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from django.utils.encoding import python_2_unicode_compatible
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class Author(models.Model):
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class Meta:
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ordering = ('-pk',)
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@python_2_unicode_compatible
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@python_2_unicode_compatible
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class Article(models.Model):
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class Article(models.Model):
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author = models.ForeignKey(Author, null=True)
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headline = models.CharField(max_length=100)
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headline = models.CharField(max_length=100)
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pub_date = models.DateTimeField()
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pub_date = models.DateTimeField()
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@ -27,15 +33,3 @@ class Article(models.Model):
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def __str__(self):
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def __str__(self):
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return self.headline
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return self.headline
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@python_2_unicode_compatible
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class ArticlePKOrdering(models.Model):
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headline = models.CharField(max_length=100)
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pub_date = models.DateTimeField()
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class Meta:
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ordering = ('-pk',)
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def __str__(self):
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return self.headline
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@ -5,26 +5,29 @@ from operator import attrgetter
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from django.test import TestCase
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from django.test import TestCase
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from .models import Article, ArticlePKOrdering
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from .models import Article, Author
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class OrderingTests(TestCase):
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class OrderingTests(TestCase):
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def test_basic(self):
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def setUp(self):
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Article.objects.create(
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self.a1 = Article.objects.create(
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headline="Article 1", pub_date=datetime(2005, 7, 26)
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headline="Article 1", pub_date=datetime(2005, 7, 26)
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)
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)
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Article.objects.create(
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self.a2 = Article.objects.create(
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headline="Article 2", pub_date=datetime(2005, 7, 27)
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headline="Article 2", pub_date=datetime(2005, 7, 27)
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)
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)
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Article.objects.create(
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self.a3 = Article.objects.create(
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headline="Article 3", pub_date=datetime(2005, 7, 27)
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headline="Article 3", pub_date=datetime(2005, 7, 27)
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)
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)
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a4 = Article.objects.create(
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self.a4 = Article.objects.create(
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headline="Article 4", pub_date=datetime(2005, 7, 28)
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headline="Article 4", pub_date=datetime(2005, 7, 28)
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)
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)
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# By default, Article.objects.all() orders by pub_date descending, then
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def test_default_ordering(self):
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# headline ascending.
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"""
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By default, Article.objects.all() orders by pub_date descending, then
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headline ascending.
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.all(), [
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Article.objects.all(), [
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"Article 4",
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"Article 4",
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@ -35,8 +38,14 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Override ordering with order_by, which is in the same format as the
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# Getting a single item should work too:
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# ordering attribute in models.
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self.assertEqual(Article.objects.all()[0], self.a4)
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def test_default_ordering_override(self):
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"""
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Override ordering with order_by, which is in the same format as the
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ordering attribute in models.
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.order_by("headline"), [
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Article.objects.order_by("headline"), [
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"Article 1",
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"Article 1",
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@ -56,8 +65,11 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Only the last order_by has any effect (since they each override any
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def test_order_by_override(self):
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# previous ordering).
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"""
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Only the last order_by has any effect (since they each override any
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previous ordering).
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.order_by("id"), [
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Article.objects.order_by("id"), [
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"Article 1",
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"Article 1",
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@ -77,7 +89,10 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Use the 'stop' part of slicing notation to limit the results.
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def test_stop_slicing(self):
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"""
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Use the 'stop' part of slicing notation to limit the results.
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.order_by("headline")[:2], [
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Article.objects.order_by("headline")[:2], [
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"Article 1",
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"Article 1",
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@ -86,8 +101,11 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Use the 'stop' and 'start' parts of slicing notation to offset the
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def test_stop_start_slicing(self):
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# result list.
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"""
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Use the 'stop' and 'start' parts of slicing notation to offset the
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result list.
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.order_by("headline")[1:3], [
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Article.objects.order_by("headline")[1:3], [
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"Article 2",
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"Article 2",
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@ -96,17 +114,20 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Getting a single item should work too:
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def test_random_ordering(self):
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self.assertEqual(Article.objects.all()[0], a4)
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"""
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Use '?' to order randomly.
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# Use '?' to order randomly.
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"""
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self.assertEqual(
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self.assertEqual(
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len(list(Article.objects.order_by("?"))), 4
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len(list(Article.objects.order_by("?"))), 4
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)
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)
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# Ordering can be reversed using the reverse() method on a queryset.
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def test_reversed_ordering(self):
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# This allows you to extract things like "the last two items" (reverse
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"""
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# and then take the first two).
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Ordering can be reversed using the reverse() method on a queryset.
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This allows you to extract things like "the last two items" (reverse
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and then take the first two).
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.all().reverse()[:2], [
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Article.objects.all().reverse()[:2], [
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"Article 1",
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"Article 1",
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@ -115,7 +136,10 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# Ordering can be based on fields included from an 'extra' clause
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def test_extra_ordering(self):
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"""
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Ordering can be based on fields included from an 'extra' clause
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.extra(select={"foo": "pub_date"}, order_by=["foo", "headline"]), [
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Article.objects.extra(select={"foo": "pub_date"}, order_by=["foo", "headline"]), [
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"Article 1",
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"Article 1",
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@ -126,8 +150,11 @@ class OrderingTests(TestCase):
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attrgetter("headline")
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attrgetter("headline")
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)
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)
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# If the extra clause uses an SQL keyword for a name, it will be
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def test_extra_ordering_quoting(self):
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# protected by quoting.
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"""
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If the extra clause uses an SQL keyword for a name, it will be
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protected by quoting.
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"""
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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Article.objects.extra(select={"order": "pub_date"}, order_by=["order", "headline"]), [
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Article.objects.extra(select={"order": "pub_date"}, order_by=["order", "headline"]), [
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"Article 1",
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"Article 1",
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@ -143,21 +170,32 @@ class OrderingTests(TestCase):
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Ensure that 'pk' works as an ordering option in Meta.
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Ensure that 'pk' works as an ordering option in Meta.
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Refs #8291.
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Refs #8291.
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"""
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"""
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ArticlePKOrdering.objects.create(
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Author.objects.create(pk=1)
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pk=1, headline="Article 1", pub_date=datetime(2005, 7, 26)
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Author.objects.create(pk=2)
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)
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Author.objects.create(pk=3)
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ArticlePKOrdering.objects.create(
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Author.objects.create(pk=4)
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pk=2, headline="Article 2", pub_date=datetime(2005, 7, 27)
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)
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ArticlePKOrdering.objects.create(
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pk=3, headline="Article 3", pub_date=datetime(2005, 7, 27)
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)
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ArticlePKOrdering.objects.create(
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pk=4, headline="Article 4", pub_date=datetime(2005, 7, 28)
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)
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self.assertQuerysetEqual(
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self.assertQuerysetEqual(
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ArticlePKOrdering.objects.all(), [
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Author.objects.all(), [
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4, 3, 2, 1
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],
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attrgetter("pk")
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)
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def test_order_by_fk_attname(self):
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"""
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Ensure that ordering by a foreign key by its attribute name prevents
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the query from inheriting it's related model ordering option.
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Refs #19195.
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"""
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for i in range(1, 5):
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author = Author.objects.create(pk=i)
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article = getattr(self, "a%d" % (5 - i))
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article.author = author
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article.save(update_fields={'author'})
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self.assertQuerysetEqual(
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Article.objects.order_by('author_id'), [
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"Article 4",
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"Article 4",
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"Article 3",
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"Article 3",
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"Article 2",
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"Article 2",
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