mirror of
https://github.com/django/django.git
synced 2024-12-22 09:05:43 +00:00
Fixed #27719 -- Added QuerySet.alias() to allow creating reusable aliases.
QuerySet.alias() allows creating reusable aliases for expressions that don't need to be selected but are used for filtering, ordering, or as a part of complex expressions. Thanks Simon Charette for reviews.
This commit is contained in:
Alexandr Tatarinov
Mariusz Felisiak
parent
88af11c58b
commit
f4ac167119
2
AUTHORS
2
AUTHORS
@ -41,7 +41,7 @@ answer newbie questions, and generally made Django that much better:
|
||||
Aleksi Häkli <aleksi.hakli@iki.fi>
|
||||
Alexander Dutton <dev@alexdutton.co.uk>
|
||||
Alexander Myodov <alex@myodov.com>
|
||||
Alexandr Tatarinov <tatarinov1997@gmail.com>
|
||||
Alexandr Tatarinov <tatarinov.dev@gmail.com>
|
||||
Alex Aktsipetrov <alex.akts@gmail.com>
|
||||
Alex Becker <https://alexcbecker.net/>
|
||||
Alex Couper <http://alexcouper.com/>
|
||||
|
||||
@ -1085,6 +1085,16 @@ class QuerySet:
|
||||
with extra data or aggregations.
|
||||
"""
|
||||
self._not_support_combined_queries('annotate')
|
||||
return self._annotate(args, kwargs, select=True)
|
||||
|
||||
def alias(self, *args, **kwargs):
|
||||
"""
|
||||
Return a query set with added aliases for extra data or aggregations.
|
||||
"""
|
||||
self._not_support_combined_queries('alias')
|
||||
return self._annotate(args, kwargs, select=False)
|
||||
|
||||
def _annotate(self, args, kwargs, select=True):
|
||||
self._validate_values_are_expressions(args + tuple(kwargs.values()), method_name='annotate')
|
||||
annotations = {}
|
||||
for arg in args:
|
||||
@ -1114,8 +1124,9 @@ class QuerySet:
|
||||
if isinstance(annotation, FilteredRelation):
|
||||
clone.query.add_filtered_relation(annotation, alias)
|
||||
else:
|
||||
clone.query.add_annotation(annotation, alias, is_summary=False)
|
||||
|
||||
clone.query.add_annotation(
|
||||
annotation, alias, is_summary=False, select=select,
|
||||
)
|
||||
for alias, annotation in clone.query.annotations.items():
|
||||
if alias in annotations and annotation.contains_aggregate:
|
||||
if clone._fields is None:
|
||||
|
||||
@ -1015,11 +1015,14 @@ class Query(BaseExpression):
|
||||
alias = seen[int_model] = join_info.joins[-1]
|
||||
return alias or seen[None]
|
||||
|
||||
def add_annotation(self, annotation, alias, is_summary=False):
|
||||
def add_annotation(self, annotation, alias, is_summary=False, select=True):
|
||||
"""Add a single annotation expression to the Query."""
|
||||
annotation = annotation.resolve_expression(self, allow_joins=True, reuse=None,
|
||||
summarize=is_summary)
|
||||
self.append_annotation_mask([alias])
|
||||
if select:
|
||||
self.append_annotation_mask([alias])
|
||||
else:
|
||||
self.set_annotation_mask(set(self.annotation_select).difference({alias}))
|
||||
self.annotations[alias] = annotation
|
||||
|
||||
def resolve_expression(self, query, *args, **kwargs):
|
||||
@ -1707,6 +1710,11 @@ class Query(BaseExpression):
|
||||
# which is executed as a wrapped subquery if any of the
|
||||
# aggregate() elements reference an existing annotation. In
|
||||
# that case we need to return a Ref to the subquery's annotation.
|
||||
if name not in self.annotation_select:
|
||||
raise FieldError(
|
||||
"Cannot aggregate over the '%s' alias. Use annotate() "
|
||||
"to promote it." % name
|
||||
)
|
||||
return Ref(name, self.annotation_select[name])
|
||||
else:
|
||||
return annotation
|
||||
@ -1911,6 +1919,11 @@ class Query(BaseExpression):
|
||||
# For lookups spanning over relationships, show the error
|
||||
# from the model on which the lookup failed.
|
||||
raise
|
||||
elif name in self.annotations:
|
||||
raise FieldError(
|
||||
"Cannot select the '%s' alias. Use annotate() to promote "
|
||||
"it." % name
|
||||
)
|
||||
else:
|
||||
names = sorted([
|
||||
*get_field_names_from_opts(opts), *self.extra,
|
||||
|
||||
@ -268,6 +268,42 @@ control the name of the annotation::
|
||||
For an in-depth discussion of aggregation, see :doc:`the topic guide on
|
||||
Aggregation </topics/db/aggregation>`.
|
||||
|
||||
``alias()``
|
||||
~~~~~~~~~~~
|
||||
|
||||
.. method:: alias(*args, **kwargs)
|
||||
|
||||
.. versionadded:: 3.2
|
||||
|
||||
Same as :meth:`annotate`, but instead of annotating objects in the
|
||||
``QuerySet``, saves the expression for later reuse with other ``QuerySet``
|
||||
methods. This is useful when the result of the expression itself is not needed
|
||||
but it is used for filtering, ordering, or as a part of a complex expression.
|
||||
Not selecting the unused value removes redundant work from the database which
|
||||
should result in better performance.
|
||||
|
||||
For example, if you want to find blogs with more than 5 entries, but are not
|
||||
interested in the exact number of entries, you could do this::
|
||||
|
||||
>>> from django.db.models import Count
|
||||
>>> blogs = Blog.objects.alias(entries=Count('entry')).filter(entries__gt=5)
|
||||
|
||||
``alias()`` can be used in conjunction with :meth:`annotate`, :meth:`exclude`,
|
||||
:meth:`filter`, :meth:`order_by`, and :meth:`update`. To use aliased expression
|
||||
with other methods (e.g. :meth:`aggregate`), you must promote it to an
|
||||
annotation::
|
||||
|
||||
Blog.objects.alias(entries=Count('entry')).annotate(
|
||||
entries=F('entries'),
|
||||
).aggregate(Sum('entries'))
|
||||
|
||||
:meth:`filter` and :meth:`order_by` can take expressions directly, but
|
||||
expression construction and usage often does not happen in the same place (for
|
||||
example, ``QuerySet`` method creates expressions, for later use in views).
|
||||
``alias()`` allows building complex expressions incrementally, possibly
|
||||
spanning multiple methods and modules, refer to the expression parts by their
|
||||
aliases and only use :meth:`annotate` for the final result.
|
||||
|
||||
``order_by()``
|
||||
~~~~~~~~~~~~~~
|
||||
|
||||
|
||||
@ -269,6 +269,10 @@ Models
|
||||
:py:class:`datetime.time`, :py:class:`datetime.timedelta`,
|
||||
:py:class:`decimal.Decimal`, and :py:class:`uuid.UUID` instances.
|
||||
|
||||
* The new :meth:`.QuerySet.alias` method allows creating reusable aliases for
|
||||
expressions that don't need to be selected but are used for filtering,
|
||||
ordering, or as a part of complex expressions.
|
||||
|
||||
Requests and Responses
|
||||
~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
|
||||
@ -10,7 +10,7 @@ from django.db.models import (
|
||||
Subquery, Sum, Value, When,
|
||||
)
|
||||
from django.db.models.expressions import RawSQL
|
||||
from django.db.models.functions import Length, Lower
|
||||
from django.db.models.functions import Coalesce, Length, Lower
|
||||
from django.test import TestCase, skipUnlessDBFeature
|
||||
|
||||
from .models import (
|
||||
@ -664,3 +664,225 @@ class NonAggregateAnnotationTestCase(TestCase):
|
||||
{'name': 'Paul Bissex', 'max_pages': 0},
|
||||
{'name': 'Wesley J. Chun', 'max_pages': 0},
|
||||
])
|
||||
|
||||
|
||||
class AliasTests(TestCase):
|
||||
@classmethod
|
||||
def setUpTestData(cls):
|
||||
cls.a1 = Author.objects.create(name='Adrian Holovaty', age=34)
|
||||
cls.a2 = Author.objects.create(name='Jacob Kaplan-Moss', age=35)
|
||||
cls.a3 = Author.objects.create(name='James Bennett', age=34)
|
||||
cls.a4 = Author.objects.create(name='Peter Norvig', age=57)
|
||||
cls.a5 = Author.objects.create(name='Stuart Russell', age=46)
|
||||
p1 = Publisher.objects.create(name='Apress', num_awards=3)
|
||||
|
||||
cls.b1 = Book.objects.create(
|
||||
isbn='159059725', pages=447, rating=4.5, price=Decimal('30.00'),
|
||||
contact=cls.a1, publisher=p1, pubdate=datetime.date(2007, 12, 6),
|
||||
name='The Definitive Guide to Django: Web Development Done Right',
|
||||
)
|
||||
cls.b2 = Book.objects.create(
|
||||
isbn='159059996', pages=300, rating=4.0, price=Decimal('29.69'),
|
||||
contact=cls.a3, publisher=p1, pubdate=datetime.date(2008, 6, 23),
|
||||
name='Practical Django Projects',
|
||||
)
|
||||
cls.b3 = Book.objects.create(
|
||||
isbn='013790395', pages=1132, rating=4.0, price=Decimal('82.80'),
|
||||
contact=cls.a4, publisher=p1, pubdate=datetime.date(1995, 1, 15),
|
||||
name='Artificial Intelligence: A Modern Approach',
|
||||
)
|
||||
cls.b4 = Book.objects.create(
|
||||
isbn='155860191', pages=946, rating=5.0, price=Decimal('75.00'),
|
||||
contact=cls.a4, publisher=p1, pubdate=datetime.date(1991, 10, 15),
|
||||
name='Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp',
|
||||
)
|
||||
cls.b1.authors.add(cls.a1, cls.a2)
|
||||
cls.b2.authors.add(cls.a3)
|
||||
cls.b3.authors.add(cls.a4, cls.a5)
|
||||
cls.b4.authors.add(cls.a4)
|
||||
|
||||
Store.objects.create(
|
||||
name='Amazon.com',
|
||||
original_opening=datetime.datetime(1994, 4, 23, 9, 17, 42),
|
||||
friday_night_closing=datetime.time(23, 59, 59)
|
||||
)
|
||||
Store.objects.create(
|
||||
name='Books.com',
|
||||
original_opening=datetime.datetime(2001, 3, 15, 11, 23, 37),
|
||||
friday_night_closing=datetime.time(23, 59, 59)
|
||||
)
|
||||
|
||||
def test_basic_alias(self):
|
||||
qs = Book.objects.alias(is_book=Value(1))
|
||||
self.assertIs(hasattr(qs.first(), 'is_book'), False)
|
||||
|
||||
def test_basic_alias_annotation(self):
|
||||
qs = Book.objects.alias(
|
||||
is_book_alias=Value(1),
|
||||
).annotate(is_book=F('is_book_alias'))
|
||||
self.assertIs(hasattr(qs.first(), 'is_book_alias'), False)
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.is_book, 1)
|
||||
|
||||
def test_basic_alias_f_annotation(self):
|
||||
qs = Book.objects.alias(
|
||||
another_rating_alias=F('rating')
|
||||
).annotate(another_rating=F('another_rating_alias'))
|
||||
self.assertIs(hasattr(qs.first(), 'another_rating_alias'), False)
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.another_rating, book.rating)
|
||||
|
||||
def test_alias_after_annotation(self):
|
||||
qs = Book.objects.annotate(
|
||||
is_book=Value(1),
|
||||
).alias(is_book_alias=F('is_book'))
|
||||
book = qs.first()
|
||||
self.assertIs(hasattr(book, 'is_book'), True)
|
||||
self.assertIs(hasattr(book, 'is_book_alias'), False)
|
||||
|
||||
def test_overwrite_annotation_with_alias(self):
|
||||
qs = Book.objects.annotate(is_book=Value(1)).alias(is_book=F('is_book'))
|
||||
self.assertIs(hasattr(qs.first(), 'is_book'), False)
|
||||
|
||||
def test_overwrite_alias_with_annotation(self):
|
||||
qs = Book.objects.alias(is_book=Value(1)).annotate(is_book=F('is_book'))
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.is_book, 1)
|
||||
|
||||
def test_alias_annotation_expression(self):
|
||||
qs = Book.objects.alias(
|
||||
is_book_alias=Value(1),
|
||||
).annotate(is_book=Coalesce('is_book_alias', 0))
|
||||
self.assertIs(hasattr(qs.first(), 'is_book_alias'), False)
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.is_book, 1)
|
||||
|
||||
def test_alias_default_alias_expression(self):
|
||||
qs = Author.objects.alias(
|
||||
Sum('book__pages'),
|
||||
).filter(book__pages__sum__gt=2000)
|
||||
self.assertIs(hasattr(qs.first(), 'book__pages__sum'), False)
|
||||
self.assertSequenceEqual(qs, [self.a4])
|
||||
|
||||
def test_joined_alias_annotation(self):
|
||||
qs = Book.objects.select_related('publisher').alias(
|
||||
num_awards_alias=F('publisher__num_awards'),
|
||||
).annotate(num_awards=F('num_awards_alias'))
|
||||
self.assertIs(hasattr(qs.first(), 'num_awards_alias'), False)
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.num_awards, book.publisher.num_awards)
|
||||
|
||||
def test_alias_annotate_with_aggregation(self):
|
||||
qs = Book.objects.alias(
|
||||
is_book_alias=Value(1),
|
||||
rating_count_alias=Count('rating'),
|
||||
).annotate(
|
||||
is_book=F('is_book_alias'),
|
||||
rating_count=F('rating_count_alias'),
|
||||
)
|
||||
book = qs.first()
|
||||
self.assertIs(hasattr(book, 'is_book_alias'), False)
|
||||
self.assertIs(hasattr(book, 'rating_count_alias'), False)
|
||||
for book in qs:
|
||||
with self.subTest(book=book):
|
||||
self.assertEqual(book.is_book, 1)
|
||||
self.assertEqual(book.rating_count, 1)
|
||||
|
||||
def test_filter_alias_with_f(self):
|
||||
qs = Book.objects.alias(
|
||||
other_rating=F('rating'),
|
||||
).filter(other_rating=4.5)
|
||||
self.assertIs(hasattr(qs.first(), 'other_rating'), False)
|
||||
self.assertSequenceEqual(qs, [self.b1])
|
||||
|
||||
def test_filter_alias_with_double_f(self):
|
||||
qs = Book.objects.alias(
|
||||
other_rating=F('rating'),
|
||||
).filter(other_rating=F('rating'))
|
||||
self.assertIs(hasattr(qs.first(), 'other_rating'), False)
|
||||
self.assertEqual(qs.count(), Book.objects.count())
|
||||
|
||||
def test_filter_alias_agg_with_double_f(self):
|
||||
qs = Book.objects.alias(
|
||||
sum_rating=Sum('rating'),
|
||||
).filter(sum_rating=F('sum_rating'))
|
||||
self.assertIs(hasattr(qs.first(), 'sum_rating'), False)
|
||||
self.assertEqual(qs.count(), Book.objects.count())
|
||||
|
||||
def test_update_with_alias(self):
|
||||
Book.objects.alias(
|
||||
other_rating=F('rating') - 1,
|
||||
).update(rating=F('other_rating'))
|
||||
self.b1.refresh_from_db()
|
||||
self.assertEqual(self.b1.rating, 3.5)
|
||||
|
||||
def test_order_by_alias(self):
|
||||
qs = Author.objects.alias(other_age=F('age')).order_by('other_age')
|
||||
self.assertIs(hasattr(qs.first(), 'other_age'), False)
|
||||
self.assertQuerysetEqual(qs, [34, 34, 35, 46, 57], lambda a: a.age)
|
||||
|
||||
def test_order_by_alias_aggregate(self):
|
||||
qs = Author.objects.values('age').alias(age_count=Count('age')).order_by('age_count', 'age')
|
||||
self.assertIs(hasattr(qs.first(), 'age_count'), False)
|
||||
self.assertQuerysetEqual(qs, [35, 46, 57, 34], lambda a: a['age'])
|
||||
|
||||
def test_dates_alias(self):
|
||||
qs = Book.objects.alias(
|
||||
pubdate_alias=F('pubdate'),
|
||||
).dates('pubdate_alias', 'month')
|
||||
self.assertCountEqual(qs, [
|
||||
datetime.date(1991, 10, 1),
|
||||
datetime.date(1995, 1, 1),
|
||||
datetime.date(2007, 12, 1),
|
||||
datetime.date(2008, 6, 1),
|
||||
])
|
||||
|
||||
def test_datetimes_alias(self):
|
||||
qs = Store.objects.alias(
|
||||
original_opening_alias=F('original_opening'),
|
||||
).datetimes('original_opening_alias', 'year')
|
||||
self.assertCountEqual(qs, [
|
||||
datetime.datetime(1994, 1, 1),
|
||||
datetime.datetime(2001, 1, 1),
|
||||
])
|
||||
|
||||
def test_aggregate_alias(self):
|
||||
msg = (
|
||||
"Cannot aggregate over the 'other_age' alias. Use annotate() to "
|
||||
"promote it."
|
||||
)
|
||||
with self.assertRaisesMessage(FieldError, msg):
|
||||
Author.objects.alias(
|
||||
other_age=F('age'),
|
||||
).aggregate(otherage_sum=Sum('other_age'))
|
||||
|
||||
def test_defer_only_alias(self):
|
||||
qs = Book.objects.alias(rating_alias=F('rating') - 1)
|
||||
msg = "Book has no field named 'rating_alias'"
|
||||
for operation in ['defer', 'only']:
|
||||
with self.subTest(operation=operation):
|
||||
with self.assertRaisesMessage(FieldDoesNotExist, msg):
|
||||
getattr(qs, operation)('rating_alias').first()
|
||||
|
||||
@skipUnlessDBFeature('can_distinct_on_fields')
|
||||
def test_distinct_on_alias(self):
|
||||
qs = Book.objects.alias(rating_alias=F('rating') - 1)
|
||||
msg = "Cannot resolve keyword 'rating_alias' into field."
|
||||
with self.assertRaisesMessage(FieldError, msg):
|
||||
qs.distinct('rating_alias').first()
|
||||
|
||||
def test_values_alias(self):
|
||||
qs = Book.objects.alias(rating_alias=F('rating') - 1)
|
||||
msg = (
|
||||
"Cannot select the 'rating_alias' alias. Use annotate() to "
|
||||
"promote it."
|
||||
)
|
||||
for operation in ['values', 'values_list']:
|
||||
with self.subTest(operation=operation):
|
||||
with self.assertRaisesMessage(FieldError, msg):
|
||||
getattr(qs, operation)('rating_alias')
|
||||
|
||||
@ -574,6 +574,7 @@ class ManagerTest(SimpleTestCase):
|
||||
'filter',
|
||||
'aggregate',
|
||||
'annotate',
|
||||
'alias',
|
||||
'complex_filter',
|
||||
'exclude',
|
||||
'in_bulk',
|
||||
|
||||
@ -303,6 +303,7 @@ class QuerySetSetOperationTests(TestCase):
|
||||
combinators.append('intersection')
|
||||
for combinator in combinators:
|
||||
for operation in (
|
||||
'alias',
|
||||
'annotate',
|
||||
'defer',
|
||||
'delete',
|
||||
|
||||
Loading…
Reference in New Issue
Block a user