Hi,
The following ticket will try to highlight a problem that I have found when using the 'OR' operator on Q objects in the boulder-oracle-sprint branch.
My model looks like this.
class Test(models.Model):
num = models.IntegerField()
def __str__(self):
return 'num=%d'%self.num
The following code will highlight the bug:
In [1]: from testapp.models import *
In [2]: from django.db.models import Q
In [3]: for i in [4,8,12]:
...: Test(num=i).save()
...:
In [4]: Test.objects.filter(num__lt=4)
Out[4]: []
In [5]: Test.objects.filter(num__gt=8, num__lt=12)
Out[5]: []
In [6]: Test.objects.filter(Q(num__lt = 4) | Q(num__gt=8, num__lt=12))
Out[6]: [<Test: num=12>, <Test: num=4>, <Test: num=8>]
In [7]: Test.objects.filter(Q(num__gt=8, num__lt=12) | Q(num__lt = 4))
Out[7]: [<Test: num=12>, <Test: num=4>, <Test: num=8>]
In [8]: Test.objects.filter(Q(num__gt=8) & Q(num__lt=12) | Q(num__lt = 4))
Out[8]: []
Lines 6 and 7 illustrate the bug.
The query appears to indicate that there are three Test objects where 'num' is less than 4 or, greater than 8 and less than 12.
Lines 4 and 5 show that no such object should exist.
Line 8 shows how I would expect the query to run.
The following is the formated (but otherwise unmodified) SQL query produced by django.
SELECT *
FROM "TESTAPP_TEST"
WHERE (("TESTAPP_TEST"."NUM" < 4 OR
"TESTAPP_TEST"."NUM" > 8 OR
"TESTAPP_TEST"."NUM" < 12))
The issue is that the second 'OR' operator should be an AND operator. Also for the sake of safety/sanity I feel that queries specified within the Q objects should also be surrounded by a bracket.
The corrected query should read
SELECT *
FROM "TESTAPP_TEST"
WHERE ((("TESTAPP_TEST"."NUM" < 4) OR
("TESTAPP_TEST"."NUM" > 8 AND
"TESTAPP_TEST"."NUM" < 12)))
Regards
Ben
