Opened 6 years ago

Closed 6 years ago

#29911 closed New feature (needsinfo)

Standardize delete_cached_value API on model Fields

Reported by: Taylor H Owned by: nobody
Component: Database layer (models, ORM) Version: 2.1
Severity: Normal Keywords:
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description (last modified by Taylor H)

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

Change History (5)

comment:1 by Taylor H, 6 years ago

Description: modified (diff)
Summary: Standardize delete_cached_value API on model FieldsStandardize `delete_cached_value API` on model Fields

comment:2 by Taylor H, 6 years ago

Summary: Standardize `delete_cached_value API` on model FieldsStandardize delete_cached_value API on model Fields

comment:3 by Tim Graham, 6 years ago

Could you detail a bit more about what your use case looks like? It's not clear to me what changes in Django are needed to solve it.

comment:4 by Tim Graham, 6 years ago

Comment from Carlton Gibson: "My initial thought here is just to override refresh_from_db(). I appreciate that’s slightly more involved than just using the field on the model, but it does mean no extra API in Django. "

comment:5 by Carlton Gibson, 6 years ago

Resolution: needsinfo
Status: newclosed

Hi taylor, I'm going to close this as-is. If you can follow-up with answers to the questions we may re-open. Thanks.

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