#35780: ForeignKey choices in admin have no option to avoid lazy evaluation of
model attributes
-------------------------------------+-------------------------------------
Reporter: Andrew Udvare | Type:
| Cleanup/optimization
Status: new | Component:
| Uncategorized
Version: 5.1 | Severity: Normal
Keywords: admin | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
https://github.com/django/django/blob/main/django/db/models/fields/__init__.py#L1073
It would be great if after the above line a value passed in the field
(such as `ForeignKey`) could be used to specify items to pass to
`select_related()` or simply to call `select_related()`. Prefetch ability
would also be good too.
In admin, there is an option for the listing `list_select_related` but no
option to make queries for choices run with select/prefetch related. An
option in `ModelAdmin` like `choices_select_related = True` would at least
call `select_related()` with no arguments above. Or it could be at the
field level with an option like `choices_select_related=('user',)` or
accept `True`. A more complex type could also be used for handling
specific fields (example with `FriendInfo` model with one-to-one with
`User`): `choices_select_related = {'best_friend': 'best_friend__user' }`,
an option for `ModelAdmin`.
Example case: If you are using a model keyed off `User` as recommended in
the docs, then in the default case, if `UserDetails.__str__` returns
`self.user.full_name`, another query has to be executed. This means for
every single user a new query has to be executed just to list them out.
Plus there may be other fields that want to list users with different
parameters. Total queries are then ''n_rel_fields * n_users + 1''.
{{{
class UserDetails(models.Model):
user = models.OneToOneField(User)
def __str__(self):
return f'{self.user.full_name}'
admin.site.register(UserDetails)
}}}
At `admin/userdetails/:id` every access of `.user` will need another query
for every user. With an argument such as `choices_select_related=True`,
`.select_related()` could be called on or after the line linked above.
--
Ticket URL: <https://code.djangoproject.com/ticket/35780>
Django <https://code.djangoproject.com/>
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 [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/0107019213438da1-322e4e80-b640-48f1-b3e9-d1e3411bc46d-000000%40eu-central-1.amazonses.com.
