[Django] #37036: TypeError when using defer() on a related manager inheriting FETCH_PEERS mode

[Django]

#37036: TypeError when using defer() on a related manager inheriting FETCH_PEERS
mode
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Type: Bug
Status: new | Component: Database
| layer (models, ORM)
Version: dev | Severity: Release
| blocker
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Using a related manager (e.g. `author.books`) inheriting a fetch mode of
`FETCH_PEERS` from its origin instance, and then chaining `defer()`, gives
a `TypeError` when trying to fetch that instance.

[https://dryorm.xterm.info/fetch-modes-bug-repro dryorm snippet]
{{{#!py
from django.db import models

class Author(models.Model):
name = models.CharField(max_length=100)

def __str__(self):
return self.name

class Book(models.Model):
author = models.ForeignKey(
Author, models.CASCADE, related_name="books"
)

def run():
plato = Author.objects.create(name='Plato')
dialogue1 = Book.objects.create(author=plato)
dialogue2 = Book.objects.create(author=plato)
for author in Author.objects.fetch_mode(models.FETCH_PEERS):
break
for book in author.books.defer("editor"):
print(book.editor)
}}}

{{{#!py
Traceback (most recent call last):
File "/django-pr/django/db/models/fields/related_descriptors.py", line
250, in __get__
rel_obj = self.field.get_cached_value(instance)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/mixins.py", line 21, in
get_cached_value
return instance._state.fields_cache[self.cache_name]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
KeyError: 'editor'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/django-pr/django/db/models/fields/__init__.py", line 2197, in
get_prep_value
return int(value)
^^^^^^^^^^
TypeError: int() argument must be a string, a bytes-like object or a real
number, not 'tuple'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/app/./manage.py", line 36, in <module>
execute_from_command_line(sys.argv)
File "/django-pr/django/core/management/__init__.py", line 443, in
execute_from_command_line
utility.execute()
File "/django-pr/django/core/management/__init__.py", line 437, in
execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/django-pr/django/core/management/base.py", line 422, in
run_from_argv
self.execute(*args, **cmd_options)
File "/django-pr/django/core/management/base.py", line 466, in execute
output = self.handle(*args, **options)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/app/management/commands/execute.py", line 292, in handle
returned = models.run()
^^^^^^^^^^^^
File "/app/app/models.py", line 24, in run
print(book.editor)
^^^^^^^^^^^
File "/django-pr/django/db/models/fields/related_descriptors.py", line
266, in __get__
instance._state.fetch_mode.fetch(self, instance)
File "/django-pr/django/db/models/fetch_modes.py", line 38, in fetch
fetcher.fetch_many(instances)
File "/django-pr/django/db/models/fields/related_descriptors.py", line
291, in fetch_many
prefetch_related_objects(missing_instances, self.field.name)
File "/django-pr/django/db/models/query.py", line 2683, in
prefetch_related_objects
obj_list, additional_lookups = prefetch_one_level(
^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/query.py", line 2858, in
prefetch_one_level
all_related_objects = list(rel_qs)
^^^^^^^^^^^^
File "/django-pr/django/db/models/query.py", line 432, in __iter__
self._fetch_all()
File "/django-pr/django/db/models/query.py", line 2229, in _fetch_all
self._result_cache = list(self._iterable_class(self))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/query.py", line 96, in __iter__
results = compiler.execute_sql(
^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 1611, in
execute_sql
sql, params = self.as_sql()
^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 795, in as_sql
self.compile(self.where) if self.where is not None else ("", [])
^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 578, in compile
sql, params = node.as_sql(self, self.connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/where.py", line 151, in as_sql
sql, params = compiler.compile(child)
^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 578, in compile
sql, params = node.as_sql(self, self.connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/tuple_lookups.py", line 148, in
as_sql
return super().as_sql(compiler, connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/lookups.py", line 551, in as_sql
return super().as_sql(compiler, connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/lookups.py", line 239, in as_sql
rhs_sql, rhs_params = self.process_rhs(compiler, connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/tuple_lookups.py", line 371, in
process_rhs
return compiler.compile(Tuple(*result))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 576, in compile
sql, params = vendor_impl(self, self.connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/tuple_lookups.py", line 46, in
as_sqlite
return self.as_sql(compiler, connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/expressions.py", line 1111, in as_sql
arg_sql, arg_params = compiler.compile(arg)
^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 576, in compile
sql, params = vendor_impl(self, self.connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/tuple_lookups.py", line 46, in
as_sqlite
return self.as_sql(compiler, connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/expressions.py", line 1111, in as_sql
arg_sql, arg_params = compiler.compile(arg)
^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/sql/compiler.py", line 576, in compile
sql, params = vendor_impl(self, self.connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/expressions.py", line 1194, in
as_sqlite
sql, params = self.as_sql(compiler, connection, **extra_context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/expressions.py", line 1179, in as_sql
val = output_field.get_db_prep_value(val, connection=connection)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/__init__.py", line 2888, in
get_db_prep_value
return value if prepared else self.get_prep_value(value)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/django-pr/django/db/models/fields/__init__.py", line 2199, in
get_prep_value
raise e.__class__(
TypeError: Field 'id' expected a number but got (None,).
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/37036>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

[Django]

#37036: TypeError when using defer() on a related manager inheriting FETCH_PEERS
mode
-------------------------------------+-------------------------------------

Reporter: Jacob Walls | Owner: (none)
Type: Bug | Status: new
Component: Database layer | Version: dev
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted

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

Changes (by Clifford Gama):

* stage: Unreviewed => Accepted


Old description:

New description:

Using a related manager (e.g. `author.books`) inheriting a fetch mode of
`FETCH_PEERS` from its origin instance, and then chaining `defer()`, gives
a `TypeError` when trying to fetch that instance.

[https://dryorm.xterm.info/fetch-modes-bug-repro dryorm snippet]
{{{#!py
from django.db import models

class Author(models.Model):
name = models.CharField(max_length=100)

def __str__(self):
return self.name

class Book(models.Model):
author = models.ForeignKey(
Author, models.CASCADE, related_name="books"
)

editor = models.ForeignKey(
Author, models.CASCADE, null=True, related_name="edited_books"

--
Ticket URL: <https://code.djangoproject.com/ticket/37036#comment:1>

[Django]

#37036: TypeError when using defer() on a related manager inheriting FETCH_PEERS
mode
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner:

| garybadwal
Type: Bug | Status: assigned

Component: Database layer | Version: dev
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by garybadwal):

* owner: (none) => garybadwal
* status: new => assigned

--
Ticket URL: <https://code.djangoproject.com/ticket/37036#comment:2>

[Django]

#37036: TypeError when using defer() on a related manager inheriting FETCH_PEERS
mode
-------------------------------------+-------------------------------------
Reporter: Jacob Walls | Owner:
| garybadwal
Type: Bug | Status: assigned
Component: Database layer | Version: dev
(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 garybadwal):

* has_patch: 0 => 1

Comment:

PR -> https://github.com/django/django/pull/21110
--
Ticket URL: <https://code.djangoproject.com/ticket/37036#comment:3>