Fixed #19360 -- Raised an explicit exception for aggregates on date/time fields in sqlite3

Thanks lsaffre for the report and Chris Medrela for the initial
patch.
This commit is contained in:
Nick Sandford 2013-01-11 13:57:54 +08:00 committed by Claude Paroz
parent 2e55cf580e
commit eb6c107624
4 changed files with 49 additions and 1 deletions

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@ -18,6 +18,8 @@ from django.db.backends.signals import connection_created
from django.db.backends.sqlite3.client import DatabaseClient
from django.db.backends.sqlite3.creation import DatabaseCreation
from django.db.backends.sqlite3.introspection import DatabaseIntrospection
from django.db.models import fields
from django.db.models.sql import aggregates
from django.utils.dateparse import parse_date, parse_datetime, parse_time
from django.utils.functional import cached_property
from django.utils.safestring import SafeBytes
@ -127,6 +129,17 @@ class DatabaseOperations(BaseDatabaseOperations):
limit = 999 if len(fields) > 1 else 500
return (limit // len(fields)) if len(fields) > 0 else len(objs)
def check_aggregate_support(self, aggregate):
bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
bad_aggregates = (aggregates.Sum, aggregates.Avg,
aggregates.Variance, aggregates.StdDev)
if (isinstance(aggregate.source, bad_fields) and
isinstance(aggregate, bad_aggregates)):
raise NotImplementedError(
'You cannot use Sum, Avg, StdDev and Variance aggregations '
'on date/time fields in sqlite3 '
'since date/time is saved as text.')
def date_extract_sql(self, lookup_type, field_name):
# sqlite doesn't support extract, so we fake it with the user-defined
# function django_extract that's registered in connect(). Note that

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@ -2188,6 +2188,14 @@ Django provides the following aggregation functions in the
aggregate functions, see
:doc:`the topic guide on aggregation </topics/db/aggregation>`.
.. warning::
SQLite can't handle aggregation on date/time fields out of the box.
This is because there are no native date/time fields in SQLite and Django
currently emulates these features using a text field. Attempts to use
aggregation on date/time fields in SQLite will raise
``NotImplementedError``.
Avg
~~~

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@ -75,3 +75,14 @@ class Article(models.Model):
def __str__(self):
return self.headline
@python_2_unicode_compatible
class Item(models.Model):
name = models.CharField(max_length=30)
date = models.DateField()
time = models.TimeField()
last_modified = models.DateTimeField()
def __str__(self):
return self.name

View File

@ -12,6 +12,7 @@ from django.db import (backend, connection, connections, DEFAULT_DB_ALIAS,
IntegrityError, transaction)
from django.db.backends.signals import connection_created
from django.db.backends.postgresql_psycopg2 import version as pg_version
from django.db.models import fields, Sum, Avg, Variance, StdDev
from django.db.utils import ConnectionHandler, DatabaseError, load_backend
from django.test import (TestCase, skipUnlessDBFeature, skipIfDBFeature,
TransactionTestCase)
@ -362,6 +363,22 @@ class EscapingChecks(TestCase):
self.assertTrue(int(response))
class SqlliteAggregationTests(TestCase):
"""
#19360: Raise NotImplementedError when aggregating on date/time fields.
"""
@unittest.skipUnless(connection.vendor == 'sqlite',
"No need to check SQLite aggregation semantics")
def test_aggregation(self):
for aggregate in (Sum, Avg, Variance, StdDev):
self.assertRaises(NotImplementedError,
models.Item.objects.all().aggregate, aggregate('time'))
self.assertRaises(NotImplementedError,
models.Item.objects.all().aggregate, aggregate('date'))
self.assertRaises(NotImplementedError,
models.Item.objects.all().aggregate, aggregate('last_modified'))
class BackendTestCase(TestCase):
def create_squares_with_executemany(self, args):
@ -400,7 +417,6 @@ class BackendTestCase(TestCase):
self.create_squares_with_executemany(args)
self.assertEqual(models.Square.objects.count(), 9)
def test_unicode_fetches(self):
#6254: fetchone, fetchmany, fetchall return strings as unicode objects
qn = connection.ops.quote_name