#29911: Standardize `delete_cached_value API` on model Fields
-------------------------------------+-------------------------------------
Reporter: Taylor Hakes | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: 2.1
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Taylor Hakes:
Old description:
> I created a custom Django model field that is expensive to calculate and
> I store a cached value on the model. I am not able to clear the cache
> when some uses the refresh_from_db() method though, since there is no
> standard API to hook into it. It appears that there is a custom behavior
> for ForeignKey that calls the delete_cached_value function, if it detects
> it's a ForeignKey
>
> https://github.com/django/django/blob/master/django/db/models/base.py#L569
>
> It would be great to allow any custom Field to implement
> `delete_cached_value` and have it called inside refresh_from_db. What are
> your thoughts? I would be happy to submit a PR if this seems reasonable
New description:
I created a custom Django model field that is expensive to calculate and I
store a cached value on the model. I am not able to clear the cache when
some uses the `refresh_from_db()` method though, since there is no
standard API to hook into it. It appears that there is a custom behavior
for `ForeignKey` that calls the `delete_cached_value` function, if it
detects it's a `ForeignKey`
https://github.com/django/django/blob/master/django/db/models/base.py#L569
It would be great to allow any custom Field to implement
`delete_cached_value` and have it called inside `refresh_from_db`. What
are your thoughts? I would be happy to submit a PR if this seems
reasonable
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Ticket URL: <https://code.djangoproject.com/ticket/29911#comment:1>
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