#27979: Bug: Using F() with mysql can leak an unwrapped OperationalError
-------------------------------------+-------------------------------------
Reporter: Chris Dary | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 1.10
Severity: Normal | Resolution:
Keywords: db, mysql, | Triage Stage:
exceptions, OperationalError | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Chris Dary:
Old description:
> Hey folks - I'm using MySQL 5.7, python 3.6, Django 1.10.
>
> I just ran into this one: It looks like with a PositiveIntegerField it's
> possible to get django to leak a raw OperationalError from mysql rather
> than a wrapped one as it's intended if you try to set it below zero. I
> assume this is a specific case of a more general issue.
>
> Here's a sample model:
>
> {{{#!python
> from django.db import models
>
> class SampleModel(models.Model):
> num = models.PositiveIntegerField()
> }}}
>
> And here's some example code showing it leaking a mysql exception which
> is not trappable by the traditional django.db exceptions (in shell_plus
> to show the queries).
>
> {{{#!python
> In [1]: import sys
> ...: from django.db import models
> ...:
>
> In [2]: sample = SampleModel.objects.create(num=0)
> ...:
> INSERT INTO `users_samplemodel` (`num`)
> VALUES (0)
>
> Execution time: 0.000492s [Database: default]
>
> In [3]: try:
> ...: sample.num = models.F('num') - 1
> ...: sample.save()
> ...: except:
> ...: err_type, error, traceback = sys.exc_info()
> ...: print("Caught Exception of type: %s" % err_type)
> ...: print("Error: %s" % error)
> ...:
> UPDATE `users_samplemodel`
> SET `num` = (`users_samplemodel`.`num` - 1)
> WHERE `users_samplemodel`.`id` = 2
>
> Execution time: 0.000409s [Database: default]
>
> Caught Exception of type: <class '_mysql_exceptions.OperationalError'>
> Error: (1690, "BIGINT UNSIGNED value is out of range in
> '(`limbo`.`users_samplemodel`.`num` - 1)'")
> }}}
>
> Looks like this just needs to be trapped and wrapped somewhere?
>
> I was able to work around it just by using a transaction and checking
> exists() first, but thought it'd be helpful to report.
>
> Thanks for all your work on Django!
New description:
Hey folks - I'm using MySQL 5.7, python 3.6, Django 1.10.
I just ran into this one: It looks like with a PositiveIntegerField it's
possible to get django to leak a raw OperationalError from mysql rather
than a wrapped one as it's intended if you try to set it below zero. I
assume this is a specific case of a more general issue.
Here's a sample model:
{{{#!python
from django.db import models
class SampleModel(models.Model):
num = models.PositiveIntegerField()
}}}
And here's some example code showing it leaking a mysql exception which is
not trappable by the traditional django.db exceptions (in shell_plus to
show the queries).
{{{#!python
In [1]: import sys
...: from django.db import models
...:
In [2]: sample = SampleModel.objects.create(num=0)
...:
INSERT INTO `users_samplemodel` (`num`)
VALUES (0)
Execution time: 0.000492s [Database: default]
In [3]: try:
...: sample.num = models.F('num') - 1
...: sample.save()
...: except:
...: err_type, error, traceback = sys.exc_info()
...: print("Caught Exception of type: %s" % err_type)
...: print("Error: %s" % error)
...:
UPDATE `users_samplemodel`
SET `num` = (`users_samplemodel`.`num` - 1)
WHERE `users_samplemodel`.`id` = 2
Execution time: 0.000409s [Database: default]
Caught Exception of type: <class '_mysql_exceptions.OperationalError'>
Error: (1690, "BIGINT UNSIGNED value is out of range in
'(`sample`.`users_samplemodel`.`num` - 1)'")
}}}
Looks like this just needs to be trapped and wrapped somewhere?
I was able to work around it just by using a transaction and checking
exists() first, but thought it'd be helpful to report.
Thanks for all your work on Django!
--
--
Ticket URL: <https://code.djangoproject.com/ticket/27979#comment:1>
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