8000 Fixed #24649 -- Allowed using Avg aggregate on non-numeric field types. · ddriddle/django@2d76b61 · GitHub
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Fixed #24649 -- Allowed using Avg aggregate on non-numeric field types.
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+46
-15
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‎django/db/backends/base/features.py

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@@ -160,6 +160,9 @@ class BaseDatabaseFeatures(object):
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# Support for the DISTINCT ON clause
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can_distinct_on_fields = False
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# Can the backend use an Avg aggregate on DurationField?
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can_avg_on_durationfield = True
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# Does the backend decide to commit before SAVEPOINT statements
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# when autocommit is disabled? http://bugs.python.org/issue8145#msg109965
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autocommits_when_autocommit_is_off = False

‎django/db/backends/oracle/features.py

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@@ -40,6 +40,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
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uppercases_column_names = True
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# select for update with limit can be achieved on Oracle, but not with the current backend.
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supports_select_for_update_with_limit = False
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can_avg_on_durationfield = False # Pending implementation (#24699).
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def introspected_boolean_field_type(self, field=None, created_separately=False):
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"""

‎django/db/models/aggregates.py

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@@ -75,12 +75,8 @@ class Avg(Aggregate):
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name = 'Avg'
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def __init__(self, expression, **extra):
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super(Avg, self).__init__(expression, output_field=FloatField(), **extra)
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def convert_value(self, value, expression, connection, context):
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if value is None:
< 8000 code>82-
return value
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return float(value)
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output_field = extra.pop('output_field', FloatField())
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super(Avg, self).__init__(expression, output_field=output_field, **extra)
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class Count(Aggregate):

‎docs/ref/models/querysets.txt

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@@ -2802,12 +2802,19 @@ by the aggregate.
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Avg
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~~~
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.. class:: Avg(expression, output_field=None, **extra)
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.. class:: Avg(expression, output_field=FloatField(), **extra)
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Returns the mean value of the given expression, which must be numeric.
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Returns the mean value of the given expression, which must be numeric
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unless you specify a different ``output_field``.
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* Default alias: ``<field>__avg``
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* Return type: ``float``
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* Return type: ``float`` (or the type of whatever ``output_field`` is
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specified)
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.. versionchanged:: 1.9
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The ``output_field`` parameter was added to allow aggregating over
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non-numeric columns, such as ``DurationField``.
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Count
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~~~~~

‎docs/releases/1.9.txt

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@@ -200,6 +200,10 @@ Models
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(such as :lookup:`exact`, :lookup:`gt`, :lookup:`lt`, etc.). For example:
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``Entry.objects.filter(pub_date__month__gt=6)``.
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203+
* You can specify the ``output_field`` parameter of the
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:class:`~django.db.models.Avg` aggregate in order to aggregate over
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non-numeric columns, such as ``DurationField``.
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CSRF
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^^^^
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‎tests/aggregation/models.py

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Original file line numberDiff line numberDiff line change
@@ -17,6 +17,7 @@ def __str__(self):
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class Publisher(models.Model):
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name = models.CharField(max_length=255)
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num_awards = models.IntegerField()
20+
duration = models.DurationField(blank=True, null=True)
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def __str__(self):
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return self.name

‎tests/aggregation/tests.py

1E80
Lines changed: 25 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -7,10 +7,10 @@
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from django.core.exceptions import FieldError
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from django.db import connection
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from django.db.models import (
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F, Aggregate, Avg, Count, DecimalField, FloatField, Func, IntegerField,
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Max, Min, Sum, Value,
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F, Aggregate, Avg, Count, DecimalField, DurationField, FloatField, Func,
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IntegerField, Max, Min, Sum, Value,
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)
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from django.test import TestCase, ignore_warnings
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from django.test import TestCase, ignore_warnings, skipUnlessDBFeature
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from django.test.utils import Approximate, CaptureQueriesContext
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from django.utils import six, timezone
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from django.utils.deprecation import RemovedInDjango20Warning
@@ -40,8 +40,8 @@ def setUpTestData(cls):
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cls.a8.friends.add(cls.a9)
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cls.a9.friends.add(cls.a8)
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43-
cls.p1 = Publisher.objects.create(name='Apress', num_awards=3)
44-
cls.p2 = Publisher.objects.create(name='Sams', num_awards=1)
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cls.p1 = Publisher.objects.create(name='Apress', num_awards=3, duration=datetime.timedelta(days=1))
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cls.p2 = Publisher.objects.create(name='Sams', num_awards=1, duration=datetime.timedelta(days=2))
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cls.p3 = Publisher.objects.create(name='Prentice Hall', num_awards=7)
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cls.p4 = Publisher.objects.create(name='Morgan Kaufmann', num_awards=9)
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cls.p5 = Publisher.objects.create(name="Jonno's House of Books", num_awards=0)
@@ -441,6 +441,13 @@ def test_aggregate_annotation(self):
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vals = Book.objects.annotate(num_authors=Count("authors__id")).aggregate(Avg("num_authors"))
442442
self.assertEqual(vals, {"num_authors__avg": Approximate(1.66, places=1)})
443443

444+
@skipUnlessDBFeature('can_avg_on_durationfield')
445+
def test_avg_duration_field(self):
446+
self.assertEqual(
447+
Publisher.objects.aggregate(Avg('duration', output_field=DurationField())),
448+
{'duration__avg': datetime.timedelta(1, 43200)} # 1.5 days
449+
)
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444451
def test_sum_distinct_aggregate(self):
445452
"""
446453
Sum on a distict() QuerySet should aggregate only the distinct items.
@@ -620,7 +627,14 @@ def test_more_aggregation(self):
620627
self.assertEqual(vals, {"rating__avg": 4.25})
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622629
def test_even_more_aggregate(self):
623-
publishers = Publisher.objects.annotate(earliest_book=Min("book__pubdate")).exclude(earliest_book=None).order_by("earliest_book").values()
630+
publishers = Publisher.objects.annotate(
631+
earliest_book=Min("book__pubdate"),
632+
).exclude(earliest_book=None).order_by("earliest_book").values(
633+
'earliest_book',
634+
'num_awards',
635+
'id',
636+
'name',
637+
)
624638
self.assertEqual(
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list(publishers), [
626640
{
@@ -836,6 +850,11 @@ def test_aggregation_expressions(self):
836850
self.assertEqual(a2, {'av_age': 37})
837851
self.assertEqual(a3, {'av_age': Approximate(37.4, places=1)})
838852

853+
def test_avg_decimal_field(self):
854+
v = Book.objects.filter(rating=4).aggregate(avg_price=(Avg('price')))['avg_price']
855+
self.assertIsInstance(v, float)
856+
self.assertEqual(v, Approximate(47.39, places=2))
857+
839858
def test_order_of_precedence(self):
840859
p1 = Book.objects.filter(rating=4).aggregate(avg_price=(Avg('price') + 2) * 3)
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self.assertEqual(p1, {'avg_price': Approximate(148.18, places=2)})

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