From 7737305a4f5dc5006d92dac3a61523ad6c2a523a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anssi=20K=C3=A4=C3=A4ri=C3=A4inen?= <akaariai@gmail.com>
Date: Mon, 19 Aug 2013 16:00:17 +0300
Subject: [PATCH] Fixed #12886 -- aggregation over sliced queryset
---
django/db/models/query.py | 5 ++---
django/db/models/sql/query.py | 8 ++++----
tests/aggregation/tests.py | 8 ++++++++
3 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 4069c04a14..836d394e9b 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -313,14 +313,13 @@ class QuerySet(object):
kwargs[arg.default_alias] = arg
query = self.query.clone()
-
+ force_subq = query.low_mark != 0 or query.high_mark is not None
aggregate_names = []
for (alias, aggregate_expr) in kwargs.items():
query.add_aggregate(aggregate_expr, self.model, alias,
is_summary=True)
aggregate_names.append(alias)
-
- return query.get_aggregation(using=self.db)
+ return query.get_aggregation(using=self.db, force_subq=force_subq)
def count(self):
"""
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index bb7d071f38..64648c394e 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -315,7 +315,7 @@ class Query(object):
# Return value depends on the type of the field being processed.
return self.convert_values(value, aggregate.field, connection)
- def get_aggregation(self, using):
+ def get_aggregation(self, using, force_subq=False):
"""
Returns the dictionary with the values of the existing aggregations.
"""
@@ -325,18 +325,18 @@ class Query(object):
# If there is a group by clause, aggregating does not add useful
# information but retrieves only the first row. Aggregate
# over the subquery instead.
- if self.group_by is not None:
+ if self.group_by is not None or force_subq:
from django.db.models.sql.subqueries import AggregateQuery
query = AggregateQuery(self.model)
-
obj = self.clone()
+ relabels = dict((t, 'subquery') for t in self.tables)
# Remove any aggregates marked for reduction from the subquery
# and move them to the outer AggregateQuery.
for alias, aggregate in self.aggregate_select.items():
if aggregate.is_summary:
- query.aggregate_select[alias] = aggregate
+ query.aggregate_select[alias] = aggregate.relabeled_clone(relabels)
del obj.aggregate_select[alias]
try:
diff --git a/tests/aggregation/tests.py b/tests/aggregation/tests.py
index 4d46cae766..339ccd63be 100644
--- a/tests/aggregation/tests.py
+++ b/tests/aggregation/tests.py
@@ -617,3 +617,11 @@ class BaseAggregateTestCase(TestCase):
# Check internal state
self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type)
self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type)
+
+ def test_ticket12886(self):
+ """
+ Check that aggregation over sliced queryset works correctly.
+ """
+ qs = Book.objects.all().order_by('-rating')[0:3]
+ vals = qs.aggregate(average_top3_rating=Avg('rating'))['average_top3_rating']
+ self.assertAlmostEqual(vals, 4.5, places=2)