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Fixed #28967 -- Prevented Cast to FloatField from rounding to integer on MySQL.

This commit is contained in:
Sergey Fedoseev 2017-12-28 05:16:37 +05:00 committed by Tim Graham
parent f1aa58479c
commit 44908d4d93
3 changed files with 10 additions and 3 deletions
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1
django/db/backends/mysql/operations.py
View File

@ -20,7 +20,6 @@ class DatabaseOperations(BaseDatabaseOperations):
'IntegerField': 'signed integer', 'IntegerField': 'signed integer',
'BigIntegerField': 'signed integer', 'BigIntegerField': 'signed integer',
'SmallIntegerField': 'signed integer', 'SmallIntegerField': 'signed integer',
'FloatField': 'signed',
'PositiveIntegerField': 'unsigned integer', 'PositiveIntegerField': 'unsigned integer',
'PositiveSmallIntegerField': 'unsigned integer', 'PositiveSmallIntegerField': 'unsigned integer',
} }

5
django/db/models/functions/comparison.py
View File

@ -14,6 +14,11 @@ class Cast(Func):
extra_context['db_type'] = self.output_field.cast_db_type(connection) extra_context['db_type'] = self.output_field.cast_db_type(connection)
return super().as_sql(compiler, connection, **extra_context) return super().as_sql(compiler, connection, **extra_context)
def as_mysql(self, compiler, connection):
# MySQL doesn't support explicit cast to float.
template = '(%(expressions)s + 0.0)' if self.output_field.get_internal_type() == 'FloatField' else None
return self.as_sql(compiler, connection, template=template)
def as_postgresql(self, compiler, connection): def as_postgresql(self, compiler, connection):
# CAST would be valid too, but the :: shortcut syntax is more readable. # CAST would be valid too, but the :: shortcut syntax is more readable.
return self.as_sql(compiler, connection, template='%(expressions)s::%(db_type)s') return self.as_sql(compiler, connection, template='%(expressions)s::%(db_type)s')

7
tests/db_functions/test_cast.py
View File

@ -1,4 +1,5 @@
import datetime import datetime
import decimal
from django.db import models from django.db import models
from django.db.models.expressions import Value from django.db.models.expressions import Value
@ -55,5 +56,7 @@ class CastTests(TestCase):
self.assertEqual(dates.get().cast_datetime, now) self.assertEqual(dates.get().cast_datetime, now)
def test_cast_from_python(self): def test_cast_from_python(self):
numbers = Author.objects.annotate(cast_float=Cast(0, models.FloatField())) numbers = Author.objects.annotate(cast_float=Cast(decimal.Decimal(0.125), models.FloatField()))
self.assertEqual(numbers.get().cast_float, 0.0) cast_float = numbers.get().cast_float
self.assertIsInstance(cast_float, float)
self.assertEqual(cast_float, 0.125)