Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Simon Charette):

 It's already released in Django 3.0 and won't be backported to 2.2 LTS
 since this bug has been around for a few years before getting identified
 and thus isn't a recent regression.

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Alexander Klimenko):

 Are there any plans of releasing this fix?

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-

Comment (by Mariusz Felisiak ):

 In [changeset:"6b7bd079a6fc4e84553262b65074dbe0af456b03" 6b7bd079]:
 {{{
 #!CommitTicketReference repository=""
 revision="6b7bd079a6fc4e84553262b65074dbe0af456b03"
 [3.0.x] Fixed #30796 -- Prevented select_related() from mutating a
 queryset on chaining.

 Thanks Darren Maki for the report.

 Backport of 37f8f293775d0b672da8ae369d9a4e17f1db7851 from master
 }}}

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  closed
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:  fixed
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Mariusz Felisiak ):

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


Comment:

 In [changeset:"37f8f293775d0b672da8ae369d9a4e17f1db7851" 37f8f293]:
 {{{
 #!CommitTicketReference repository=""
 revision="37f8f293775d0b672da8ae369d9a4e17f1db7851"
 Fixed #30796 -- Prevented select_related() from mutating a queryset on
 chaining.

 Thanks Darren Maki for the report.
 }}}

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

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  assigned
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  1|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Simon Charette):

 * has_patch:  0 => 1


Comment:

 Fixed in https://github.com/django/django/pull/11810

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  Simon
 |  Charette
 Type:  Bug  |   Status:  assigned
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Simon Charette):

 * status:  new => assigned
 * owner:  nobody => Simon Charette


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Ticket URL: 
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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  select_related   | Triage Stage:  Accepted
  prefetch_related mutate queryset   |
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Changes (by Simon Charette):

 * stage:  Unreviewed => Accepted


Comment:

 This seems to have been happening forever.

 `sql.Query.select_related` is made a `dict` on `.add_select_related` but
 never copied on `.clone`.

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Re: [Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
 Reporter:  Darren Maki  |Owner:  nobody
 Type:  Bug  |   Status:  new
Component:  Database layer   |  Version:  2.2
  (models, ORM)  |
 Severity:  Normal   |   Resolution:
 Keywords:  select_related   | Triage Stage:
  prefetch_related mutate queryset   |  Unreviewed
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+-
Description changed by Darren Maki:

Old description:

> When creating a new QuerySet from an existing QuerySet that has had
> 'select_related' applied, if you apply another 'select_related' to the
> new QuerySet it will mutate the original QuerySet to also have the extra
> 'select_related'.
>
> '''models.py'''
>
> {{{
> from django.db import models
>
> class ModelA(models.Model):
> pass
>
> class ModelB(models.Model):
> pass
>
> class ModelC(models.Model):
> model_a = models.ForeignKey('foobar.ModelA',
> on_delete=models.CASCADE)
> model_b = models.ForeignKey('foobar.ModelB',
> on_delete=models.CASCADE)
> }}}
>
> '''test.py'''
>
> {{{
> query_1 = ModelC.objects.select_related('model_a')
> print('QUERY 1:', str(query_1.query))
>
> query_2 = query_1.select_related('model_b')
> print('QUERY 2:', str(query_2.query))
>
> print('QUERY 1:', str(query_1.query))
>
> if str(query_1.query) == str(query_2.query):
> print('\n!!! The two queries are the same !!!\n')
> }}}
>
> '''output'''
>
> {{{
> QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
> "foobar_modelc"."model_b_id", "foobar_modela"."id" FROM "foobar_modelc"
> INNER JOIN "foobar_modela" ON ("foobar_modelc"."model_a_id" =
> "foobar_modela"."id") 139663365718536
> QUERY 2: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
> "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
> FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
> ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
> "foobar_modelb" ON ("foobar_modelc"."model_b_id" = "foobar_modelb"."id")
> 139663366175376
> QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
> "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
> FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
> ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
> "foobar_modelb" ON ("foobar_modelc"."model_b_id" = "foobar_modelb"."id")
> 139663365718536
>
> !!! The two queries are the same !!!
>
> }}}
>
> The expectation is that the original QuerySet is not mutated, and the two
> queries are different. This behavior also happens with
> 'prefetch_related'.
>
> Since the QuerySet methods call 'self._clone()', and state that they
> return 'a new QuerySet instance', this behavior does not seem correct.

New description:

 When creating a new QuerySet from an existing QuerySet that has had
 'select_related' applied, if you apply another 'select_related' to the new
 QuerySet it will mutate the original QuerySet to also have the extra
 'select_related'.

 '''models.py'''

 {{{
 from django.db import models

 class ModelA(models.Model):
 pass

 class ModelB(models.Model):
 pass

 class ModelC(models.Model):
 model_a = models.ForeignKey('foobar.ModelA', on_delete=models.CASCADE)
 model_b = models.ForeignKey('foobar.ModelB', on_delete=models.CASCADE)
 }}}

 '''test.py'''

 {{{
 query_1 = ModelC.objects.select_related('model_a')
 print('QUERY 1:', str(query_1.query))

 query_2 = query_1.select_related('model_b')
 print('QUERY 2:', str(query_2.query))

 print('QUERY 1:', str(query_1.query))

 if str(query_1.query) == str(query_2.query):
 print('\n!!! The two queries are the same !!!\n')
 }}}

 '''output'''

 {{{
 QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id" FROM "foobar_modelc"
 INNER JOIN "foobar_modela" ON ("foobar_modelc"."model_a_id" =
 "foobar_modela"."id")
 QUERY 2: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
 FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
 ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
 "foobar_modelb" ON ("foobar_modelc"."model_b_id" = "foobar_modelb"."id")
 QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
 FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
 ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
 "foobar_modelb" ON ("foobar_modelc"."model_b_id" = 

[Django] #30796: Chaining select_related mutates original QuerySet.

[Django]

#30796: Chaining select_related mutates original QuerySet.
-+-
   Reporter:  Darren |  Owner:  nobody
  Maki   |
   Type:  Bug| Status:  new
  Component:  Database   |Version:  2.2
  layer (models, ORM)|   Keywords:  select_related
   Severity:  Normal |  prefetch_related mutate queryset
   Triage Stage: |  Has patch:  0
  Unreviewed |
Needs documentation:  0  |Needs tests:  0
Patch needs improvement:  0  |  Easy pickings:  0
  UI/UX:  0  |
-+-
 When creating a new QuerySet from an existing QuerySet that has had
 'select_related' applied, if you apply another 'select_related' to the new
 QuerySet it will mutate the original QuerySet to also have the extra
 'select_related'.

 '''models.py'''

 {{{
 from django.db import models

 class ModelA(models.Model):
 pass

 class ModelB(models.Model):
 pass

 class ModelC(models.Model):
 model_a = models.ForeignKey('foobar.ModelA', on_delete=models.CASCADE)
 model_b = models.ForeignKey('foobar.ModelB', on_delete=models.CASCADE)
 }}}

 '''test.py'''

 {{{
 query_1 = ModelC.objects.select_related('model_a')
 print('QUERY 1:', str(query_1.query))

 query_2 = query_1.select_related('model_b')
 print('QUERY 2:', str(query_2.query))

 print('QUERY 1:', str(query_1.query))

 if str(query_1.query) == str(query_2.query):
 print('\n!!! The two queries are the same !!!\n')
 }}}

 '''output'''

 {{{
 QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id" FROM "foobar_modelc"
 INNER JOIN "foobar_modela" ON ("foobar_modelc"."model_a_id" =
 "foobar_modela"."id") 139663365718536
 QUERY 2: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
 FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
 ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
 "foobar_modelb" ON ("foobar_modelc"."model_b_id" = "foobar_modelb"."id")
 139663366175376
 QUERY 1: SELECT "foobar_modelc"."id", "foobar_modelc"."model_a_id",
 "foobar_modelc"."model_b_id", "foobar_modela"."id", "foobar_modelb"."id"
 FROM "foobar_modelc" INNER JOIN "foobar_modela" ON
 ("foobar_modelc"."model_a_id" = "foobar_modela"."id") INNER JOIN
 "foobar_modelb" ON ("foobar_modelc"."model_b_id" = "foobar_modelb"."id")
 139663365718536

 !!! The two queries are the same !!!

 }}}

 The expectation is that the original QuerySet is not mutated, and the two
 queries are different. This behavior also happens with 'prefetch_related'.

 Since the QuerySet methods call 'self._clone()', and state that they
 return 'a new QuerySet instance', this behavior does not seem correct.

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

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