#28268: Feature: Clear cached_property on related DB operations.
-------------------------------------+-------------------------------------
Reporter: Özer Sahin | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: 1.11
(models, ORM) |
Severity: Normal | Resolution:
Keywords: cached_property | 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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Comment (by Özer Sahin):
Here is a quick example to try to illustrate:
{{{
class ModelA(models.Model):
@cached_property
def related_count(self):
return self.related.count()
@cached_property
def related_content(self):
return ', '.join([rel.title for rel in self.related.all()])
class Related(models.Model):
model = models.ForeignKey(ModelA, related_name='related')
title = models.CharField()
>>> model = ModelA()
>>> rel = Related()
>>> rel.model = model
>>> rel.title = "Text"
>>> rel.save()
>>> model.related_count()
1 # calls first time
>>> model.related_content()
Text # calls first time
>>> rel.title = "New Text"
>>> rel.save()
>>> model.related_content()
New Text # calls, because rel changed
>>> model.related_count()
1 # does not call, because nothing was added
>>> rel.delete()
>>> model.related_count()
0 # calls, because related model removed
}}}
So what I am actually looking for, are some kind of signals to attach to
the decorator so we can input logic, when the cached_property should be
removed so it calls it again for an updated value. We could define that it
should delete the cached value once related objects were updated, deleted
or created. That way we can max out the cache, but keep it always up to
date. I think it could be a huge performance booster without the issue of
manually deleting cached_properties so they update.
I hope I am not too far off, awaiting your feedback!
--
Ticket URL: <https://code.djangoproject.com/ticket/28268#comment:2>
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