[Django] #35950: Fix refreshing of related fields when one field is deferred

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam | Owner: Adam Johnson
Johnson |
Type: Bug | Status: assigned
Component: Database | Version: 5.1
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
In #35044, we fixed the issue where loading a deferred field would clear
related objects.

But it left a bug where refreshing all fields explicitly with
`refresh_from_db()` would no longer clear related objects *if* the model
instance had any deferred fields.

This would work on Django 5.0 but is broken on 5.1:

{{{
book = Book.objects.defer('title').get(pk=1)
assert book.author is not None # fetch related object
Author.objects.all().delete()

book.refresh_from_db()
assert book.author is None # should have been reset by the refresh
}}}

Fix incoming.
--
Ticket URL: <https://code.djangoproject.com/ticket/35950>
Django <https://code.djangoproject.com/>
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[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------

Reporter: Adam Johnson | Owner: Adam

| Johnson
Type: Bug | Status: assigned

Component: Database layer | Version: 5.1
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Adam Johnson):

* has_patch: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:1>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson

Type: Bug | Status: closed

Component: Database layer | Version: 5.1

(models, ORM) | Resolution:
Severity: Normal | worksforme

Keywords: | Triage Stage:
| Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce):

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

Comment:

I've not been able to replicate following the instructions on Django 5.1.3
--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:2>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson
Type: Bug | Status: closed
Component: Database layer | Version: 5.1
(models, ORM) | Resolution:
Severity: Normal | worksforme
Keywords: | Triage Stage:
| Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Sarah Boyce):

* cc: Giannis Terzopoulos (added)

--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:3>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson

Type: Bug | Status: new

Component: Database layer | Version: 5.1
(models, ORM) |

Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Simon Charette):

* resolution: worksforme =>
* stage: Unreviewed => Accepted
* status: closed => new

Comment:

I managed to reproduce locally with
[https://github.com/django/django/pull/18860/files#diff-
51d1f447d95c1f21d5253801dc116988967499bafa107339257bcb58b2513e42R293 the
the additional test provided in the PR].
--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:4>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson
Type: Bug | Status: new
Component: Database layer | Version: 5.1
(models, ORM) |

Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 1

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce):

* needs_docs: 0 => 1
* severity: Normal => Release blocker

Comment:

Thank you - bisected to 73df8b54a2fab53bec4c7573cda5ad8c869c2fd8
Adam can you add a release note?
--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:5>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson
Type: Bug | Status: new
Component: Database layer | Version: 5.1
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Sarah Boyce):

* needs_docs: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:6>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson
Type: Bug | Status: new
Component: Database layer | Version: 5.1
(models, ORM) |
Severity: Release blocker | Resolution:

Keywords: | Triage Stage: Ready for
| checkin

Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Sarah Boyce):

* stage: Accepted => Ready for checkin

--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:7>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson

Type: Bug | Status: closed

Component: Database layer | Version: 5.1
(models, ORM) |

Severity: Release blocker | Resolution: fixed

Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce <42296566+sarahboyce@…>):

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

Comment:

In [changeset:"2f6b096b83c55317c7ceef2d8d5dc3bee33293dc" 2f6b096b]:
{{{#!CommitTicketReference repository=""
revision="2f6b096b83c55317c7ceef2d8d5dc3bee33293dc"
Fixed #35950 -- Restored refreshing of relations when fields deferred.

Thank you to Simon Charette and Sarah Boyce for the review.

Regression in 73df8b54a2fab53bec4c7573cda5ad8c869c2fd8.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:8>

[Django]

#35950: Fix refreshing of related fields when one field is deferred
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
| Johnson
Type: Bug | Status: closed
Component: Database layer | Version: 5.1
(models, ORM) |
Severity: Release blocker | Resolution: fixed
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Sarah Boyce <42296566+sarahboyce@…>):

In [changeset:"6e3e7353e00b64c61674ac7e0edc7cee761c9b15" 6e3e7353]:
{{{#!CommitTicketReference repository=""
revision="6e3e7353e00b64c61674ac7e0edc7cee761c9b15"
[5.1.x] Fixed #35950 -- Restored refreshing of relations when fields

deferred.

Thank you to Simon Charette and Sarah Boyce for the review.

Regression in 73df8b54a2fab53bec4c7573cda5ad8c869c2fd8.

Backport of 2f6b096b83c55317c7ceef2d8d5dc3bee33293dc from main.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35950#comment:9>