Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Simon Charette):

 > Please don't feel the need to add a workaround or hack for my project.
 Now that it is identified, I'm happy to fix my buggy code to rely only on
 defined behavior.
 >
 > Or are you suggesting that in a future version of Django, `RelatedExact`
 raise an exception when used with an unsaved object?

 While it was undefined I'm kind of shocked we didn't have any tests for
 this. I'm not sure if you added this test on purpose in your suite but I
 could see it happening often in cases where users mix ''model factories''
 with the ORM in tests.

 I feel like preventing unsaved objects from being used in all related
 filters in future versions of Django would be the best course of action
 here. Surprisingly erroring on `if value._state.adding` in
 
[https://github.com/django/django/blob/master/django/db/models/fields/related_lookups.py#L28
 get_normalized_values] yields quite a few test failures in the suite.
 Nothing that looks unsolvable though.

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.e2bec5bed5d010dfae9a555f9ecc7b90%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Jon Dufresne):

 Thanks Simon.

 > I assume the previous query was ...

 Yes, that is right. And looking at this again, now, I think the `=` in `=
 NULL` was certainly wrong or unintended. So it would seem I was relying on
 undefined behavior and got lucky.

 > Here's a PR implementing the EmptyResultSet approach that could be used
 in a 2.0 backport. ... I really think we should deprecating this path in
 2.1+ though

 Please don't feel the need to add a workaround or hack for my project. Now
 that it is identified, I'm happy to fix my buggy code to rely only on
 defined behavior.

 Or are you suggesting that in a future version of Django, `RelatedExact`
 raise an exception when used with an unsaved object?

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.2a1d3fba50bbdbc5fcb55255c5d32cc4%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Simon Charette):

 Here's a PR implementing the `EmptyResultSet` approach that could be used
 in a 2.0 backport.

 https://github.com/django/django/compare/master...charettes:ticket-27985

 I really think we should deprecating this path in 2.1+ though given the
 ambiguity of the lookup when `instance._state.adding`, I feel like this
 would be inline with the changes to prevent
 `instance.m2m.add(unsaved_instance)`.

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.592b153b95050da3183724560aabe342%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Simon Charette):

 * cc: Simon Charette (added)


Comment:

 John, I feel like using a `LOUTER` join is the appropriate behavior here.

 I assume the previous query was

 {{{#!sql
 SELECT *
 FROM group
 INNER JOIN user_groups ON (user_groups.group_id = group.id)
 WHERE user_groups.user_id = NULL
 }}}

 And the new one is

 {{{#!sql
 SELECT *
 FROM group
 LEFT OUTER JOIN user_groups ON (user_groups.group_id = group.id)
 WHERE user_groups.user_id IS NULL
 }}}

 Using `m2m__isnull=True` (or `reverse_fk__isnull=True`) always triggered
 this `LOUTER` AFAIK. I guess what broke here was to make `m2m=None` ->
 `m2m__isnull=True` which seems more appropriate given how SQL deals with
 `= NULL`.

 I guess we could get related and reverse related field `__exact` lookups
 to warn/error out when an unsaved object is passed as a value though, it
 looks like this was undefined behavior if it wasn't caught by the test
 suite. An other option would be to make the related
 `__exact=unsaved_object` lookup raise `EmptyResultSet` on compilation to
 prevent any query from taking place and restore the 1.11 behavior.

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.985e0a207c0632f7f3003720e595c526%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Jon Dufresne):

 This change caused a regression for my project. Here is a simplified
 example:

 {{{
 class Group(models.Model):
 pass

 class User(models.Model):
 groups = models.ManyToManyField('Group')

 class MyTest(TestCase):
 def test_unsaved(self):
 Group.objects.create()
 u = User()
 self.assertFalse(Group.objects.filter(user=u).exists())
 }}}

 This test passes on 1.11 but fails on 2.0.

 On 1.11, passing an ''unsaved'' model to a M2M filter would result in an
 `INNER JOIN`. A bisect shows that since commit
 a5c60404476124c682c996bfb1eb077d59f1ec53, it now results in a `LEFT OUTER
 JOIN`.

 At this stage, only looking for clarification on what is correct to see if
 this change in behavior is intentional. Is this now correct as a `LEFT
 JOIN` or should this be considered a regression for this specific use?

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.f0750dbc5c17df56617bc54c0d759dcc%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Tim Graham ):

 In [changeset:"10bfa876be59feec24bb6a40fa11bece808ee405" 10bfa876]:
 {{{
 #!CommitTicketReference repository=""
 revision="10bfa876be59feec24bb6a40fa11bece808ee405"
 Refs #27985 -- Reallowed using __exact=None as an alias for __isnull=True
 if a custom lookup class with lookup_name != None is registered as the
 exact lookup.

 Regression in 58da81a5a372a69f0bac801c412b57f3cce5f188 and prerequisite
 for refs #28896.
 }}}

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.25845b3d4da1b8a9f0ab437b0febd6d5%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Tim Graham ):

 In [changeset:"a5c60404476124c682c996bfb1eb077d59f1ec53" a5c6040]:
 {{{
 #!CommitTicketReference repository=""
 revision="a5c60404476124c682c996bfb1eb077d59f1ec53"
 [2.0.x] Refs #27985 -- Reallowed using __exact=None as an alias for
 __isnull=True if a custom lookup class with lookup_name != None is
 registered as the exact lookup.

 Regression in 58da81a5a372a69f0bac801c412b57f3cce5f188 and prerequisite
 for refs #28896.

 Backport of 10bfa876be59feec24bb6a40fa11bece808ee405 from master
 }}}

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.e775ef3ccfdffd30f282eb61e4e4cbbc%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Tim Graham ):

 * status:  assigned => closed
 * resolution:   => fixed


Comment:

 In [changeset:"58da81a5a372a69f0bac801c412b57f3cce5f188" 58da81a5]:
 {{{
 #!CommitTicketReference repository=""
 revision="58da81a5a372a69f0bac801c412b57f3cce5f188"
 Fixed #27985 -- Fixed query for __exact=value when get_prep_value()
 converts value to None.

 Also fixed crash of .filter(field__transform=None).
 }}}

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.812f122fb1667bfe941d8bf997fe7fb2%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  assigned
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Sergey Fedoseev):

 * has_patch:  0 => 1


Comment:

 [https://github.com/django/django/pull/8831 PR]

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.9c4aa99e16c84eaf6cd127ecef9d7f22%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Sergey
 |  Fedoseev
 Type:  Bug  |   Status:  assigned
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Sergey Fedoseev):

 * status:  new => assigned
 * owner:  (none) => Sergey Fedoseev


-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.dea0a27b73fceb4955bb2ac6dbf34aeb%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  (none)
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Jarek Glowacki):

 * owner:  Jarek Glowacki => (none)
 * status:  assigned => new


Comment:

 Yeahh, nope.
 The current workflow is too convoluted to just slot in a patch for this.

 I couldn't find a way to untangle the ordering such that it'd cover this
 use case without breaking multiple other use cases.
 I'd suggest taking this ticket under consideration when someone comes
 round to refactor this file.

 Specifically, the functions `build_filter` and `prepare_lookup_value` need
 to be broken down into more managable bits. It's evident they've had extra
 conditional steps shoehorned in over time, which has made them very
 difficult to work with.


 For anyone who comes across this in the future, all we need to address
 this case is ensure that this snippet of code from `prepare_lookup_value`:
 {{{
 # Interpret '__exact=None' as the sql 'is NULL'; otherwise, reject
 all
 # uses of None as a query value.
 if value is None:
 if lookups[-1] not in ('exact', 'iexact'):
 raise ValueError("Cannot use None as a query value")
 return True, ['isnull'], used_joins
 }}}
 is evaluated AFTER the field's `get_prep_value` has processed the value.
 Here are the failing tests again:
 [https://github.com/django/django/compare/master...jarekwg:ticket_27985
 Failing tests]

 And here's a bandaid workaround that hacks two lookups and the form field
 to get around the problem.
 {{{
 class NulledCharField(models.CharField):
 """
 This is required when we want uniqueness on a CharField whilst also
 allowing it to be empty.
 In the DB, '' == '', but NULL != NULL. So we store emptystring as NULL
 in the db, but treat it
 as emptystring in the code.
 """
 description = _("CharField that stores emptystring as NULL but returns
 ''.")

 def from_db_value(self, value, expression, connection, context):
 if value is None:
 return ''
 else:
 return value

 def to_python(self, value):
 if isinstance(value, models.CharField):
 return value
 if value is None:
 return ''
 return value

 def get_prep_value(self, value):
 if value is '':
 return None
 else:
 return value

 class NulledCharField(forms.CharField):
 """ A form field for the encompassing model field. """
 def clean(self, value):
 if value == '':
 return None
 return value

 def formfield(self, form_class=None, **kwargs):
 return
 super().formfield(form_class=self.__class__.NulledCharField, **kwargs)


 @NulledCharField.register_lookup
 class NulledCharExactLookup(Exact):
 """ Generate ISNULL in the `exact` lookup, because Django won't use
 the `isnull` lookup correctly. """
 lookup_name = 'exact'

 def as_sql(self, compiler, connection):
 sql, params = compiler.compile(self.lhs)
 if self.rhs in ('', None):
 return "%s IS NULL" % sql, params
 else:
 return super().as_sql(compiler, connection)


 @NulledCharField.register_lookup
 class NulledCharIsNullLookup(IsNull):
 """
 Doing something like Foo.objects.exclude(bar='') has django trying to
 shove
 an extra isnull check where it doesn't need one. We solve this by just
 crippling
 this lookup altogether. We don't need it as all ISNULL checks that we
 actually
 do want, we generate in the `exact` lookup. :(
 """
 lookup_name = 'isnull'
 prepare_rhs = False

 def as_sql(self, compiler, connection):
 sql, params = compiler.compile(self.lhs)
 return "TRUE", params
 }}}

--
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post 

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  Jarek
 |  Glowacki
 Type:  Bug  |   Status:  assigned
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Jarek Glowacki):

 * owner:  nobody => Jarek Glowacki
 * status:  new => assigned


--
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.9bc01b966d72bada777411e68395225a%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Jarek Glowacki):

 [https://github.com/django/django/compare/master...jarekwg:ticket_27985
 Here's a failing testcase] for now; will have a crack at writing a patch
 soon..

 Also realised it gets even messier for the `.exclude()` case, where it
 
[https://github.com/django/django/blob/master/django/db/models/sql/query.py#L1214-L1229
 adds an extra query].
 This causes a mutually exclusive pair of conditions, that'll always
 evaluate to false.
 It does this:
 `Foo.objects.exclude(bar='')` -> `... WHERE NOT ("foo"."bar" = NULL AND
 "foo"."bar" IS NOT NULL)`
 Instead of just
 `Foo.objects.exclude(bar=None)` -> `... WHERE NOT ("foo"."bar" IS NULL)`

--
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.27fc0035be2ba768244e151317df%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Re: [Django] #27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.

[Django]

#27985: Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.
-+-
 Reporter:  Jarek Glowacki   |Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  master
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  sql None NULL| Triage Stage:  Accepted
  transform  |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Tim Graham):

 * stage:  Unreviewed => Accepted


Comment:

 I haven't investigated, but please provide a patch and I'll take a closer
 look at it.

--
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/065.1fee236ec88cc2f2d33f0043f4d9086a%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.