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Fixed #13312 -- Allowed specifying the order of null fields in queries. 

Thanks Mariusz Felisiak for finishing the patch.
This commit is contained in:
Yohann Gabory 2016-07-27 15:17:05 +02:00 committed by Tim Graham
parent 82fd779af5
commit 47ef8f31f3
5 changed files with 105 additions and 13 deletions
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43
django/db/models/expressions.py
View File

@ -319,11 +319,11 @@ class BaseExpression(object):
"""
return [e._output_field_or_none for e in self.get_source_expressions()]
def asc(self):
return OrderBy(self)
def asc(self, **kwargs):
return OrderBy(self, **kwargs)
def desc(self):
return OrderBy(self, descending=True)
def desc(self, **kwargs):
return OrderBy(self, descending=True, **kwargs)
def reverse_ordering(self):
return self
@ -462,11 +462,11 @@ class F(Combinable):
def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
return query.resolve_ref(self.name, allow_joins, reuse, summarize)
def asc(self):
return OrderBy(self)
def asc(self, **kwargs):
return OrderBy(self, **kwargs)
def desc(self):
return OrderBy(self, descending=True)
def desc(self, **kwargs):
return OrderBy(self, descending=True, **kwargs)
class Func(Expression):
@ -869,7 +869,11 @@ class Case(Expression):
class OrderBy(BaseExpression):
template = '%(expression)s %(ordering)s'
def __init__(self, expression, descending=False):
def __init__(self, expression, descending=False, nulls_first=False, nulls_last=False):
if nulls_first and nulls_last:
raise ValueError('nulls_first and nulls_last are mutually exclusive')
self.nulls_first = nulls_first
self.nulls_last = nulls_last
self.descending = descending
if not hasattr(expression, 'resolve_expression'):
raise ValueError('expression must be an expression type')
@ -886,6 +890,11 @@ class OrderBy(BaseExpression):
return [self.expression]
def as_sql(self, compiler, connection, template=None, **extra_context):
if not template:
if self.nulls_last:
template = '%s NULLS LAST' % self.template
elif self.nulls_first:
template = '%s NULLS FIRST' % self.template
connection.ops.check_expression_support(self)
expression_sql, params = compiler.compile(self.expression)
placeholders = {
@ -896,6 +905,22 @@ class OrderBy(BaseExpression):
template = template or self.template
return (template % placeholders).rstrip(), params
def as_sqlite(self, compiler, connection):
template = None
if self.nulls_last:
template = '%(expression)s IS NULL, %(expression)s %(ordering)s'
elif self.nulls_first:
template = '%(expression)s IS NOT NULL, %(expression)s %(ordering)s'
return self.as_sql(compiler, connection, template=template)
def as_mysql(self, compiler, connection):
template = None
if self.nulls_last:
template = 'IF(ISNULL(%(expression)s),1,0), %(expression)s %(ordering)s '
elif self.nulls_first:
template = 'IF(ISNULL(%(expression)s),0,1), %(expression)s %(ordering)s '
return self.as_sql(compiler, connection, template=template)
def get_group_by_cols(self):
cols = []
for source in self.get_source_expressions():

16
docs/ref/models/expressions.txt
View File

@ -560,14 +560,26 @@ calling the appropriate methods on the wrapped expression.
nested expressions. ``F()`` objects, in particular, hold a reference
to a column.
.. method:: asc()
.. method:: asc(nulls_first=False, nulls_last=False)
Returns the expression ready to be sorted in ascending order.
.. method:: desc()
``nulls_first`` and ``nulls_last`` define how null values are sorted.
.. versionchanged:: 1.11
The ``nulls_last`` and ``nulls_first`` parameters were added.
.. method:: desc(nulls_first=False, nulls_last=False)
Returns the expression ready to be sorted in descending order.
``nulls_first`` and ``nulls_last`` define how null values are sorted.
.. versionchanged:: 1.11
The ``nulls_first`` and ``nulls_last`` parameters were added.
.. method:: reverse_ordering()
Returns ``self`` with any modifications required to reverse the sort

5
docs/releases/1.11.txt
View File

@ -337,6 +337,11 @@ Models
* You can now use the ``unique=True`` option with
:class:`~django.db.models.FileField`.
* Added the ``nulls_first`` and ``nulls_last`` parameters to
:class:`Expression.asc() <django.db.models.Expression.asc>` and
:meth:`~django.db.models.Expression.desc` to control
the ordering of null values.
Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~

2
tests/ordering/models.py
View File

@ -18,6 +18,8 @@ from django.utils.encoding import python_2_unicode_compatible
class Author(models.Model):
name = models.CharField(max_length=63, null=True, blank=True)
class Meta:
ordering = ('-pk',)

52
tests/ordering/tests.py
View File

@ -4,6 +4,7 @@ from datetime import datetime
from operator import attrgetter
from django.db.models import F
from django.db.models.functions import Upper
from django.test import TestCase
from .models import Article, Author, Reference
@ -17,8 +18,8 @@ class OrderingTests(TestCase):
cls.a2 = Article.objects.create(headline="Article 2", pub_date=datetime(2005, 7, 27))
cls.a3 = Article.objects.create(headline="Article 3", pub_date=datetime(2005, 7, 27))
cls.a4 = Article.objects.create(headline="Article 4", pub_date=datetime(2005, 7, 28))
cls.author_1 = Author.objects.create()
cls.author_2 = Author.objects.create()
cls.author_1 = Author.objects.create(name="Name 1")
cls.author_2 = Author.objects.create(name="Name 2")
for i in range(2):
Author.objects.create()
@ -88,6 +89,53 @@ class OrderingTests(TestCase):
attrgetter("headline")
)
def test_order_by_nulls_first_and_last(self):
msg = "nulls_first and nulls_last are mutually exclusive"
with self.assertRaisesMessage(ValueError, msg):
Article.objects.order_by(F("author").desc(nulls_last=True, nulls_first=True))
def test_order_by_nulls_last(self):
Article.objects.filter(headline="Article 3").update(author=self.author_1)
Article.objects.filter(headline="Article 4").update(author=self.author_2)
# asc and desc are chainable with nulls_last.
self.assertSequenceEqual(
Article.objects.order_by(F("author").desc(nulls_last=True)),
[self.a4, self.a3, self.a1, self.a2],
)
self.assertSequenceEqual(
Article.objects.order_by(F("author").asc(nulls_last=True)),
[self.a3, self.a4, self.a1, self.a2],
)
self.assertSequenceEqual(
Article.objects.order_by(Upper("author__name").desc(nulls_last=True)),
[self.a4, self.a3, self.a1, self.a2],
)
self.assertSequenceEqual(
Article.objects.order_by(Upper("author__name").asc(nulls_last=True)),
[self.a3, self.a4, self.a1, self.a2],
)
def test_order_by_nulls_first(self):
Article.objects.filter(headline="Article 3").update(author=self.author_1)
Article.objects.filter(headline="Article 4").update(author=self.author_2)
# asc and desc are chainable with nulls_first.
self.assertSequenceEqual(
Article.objects.order_by(F("author").asc(nulls_first=True)),
[self.a1, self.a2, self.a3, self.a4],
)
self.assertSequenceEqual(
Article.objects.order_by(F("author").desc(nulls_first=True)),
[self.a1, self.a2, self.a4, self.a3],
)
self.assertSequenceEqual(
Article.objects.order_by(Upper("author__name").asc(nulls_first=True)),
[self.a1, self.a2, self.a3, self.a4],
)
self.assertSequenceEqual(
Article.objects.order_by(Upper("author__name").desc(nulls_first=True)),
[self.a1, self.a2, self.a4, self.a3],
)
def test_stop_slicing(self):
"""
Use the 'stop' part of slicing notation to limit the results.