id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37201	Prefetch with to_attr silently ignored if matching property exists	dc-strahlkraft		"Minimal reproduction https://gitlab.com/Dan_Strahlkraft/django-prefetch

Given these models:

{{{
class Product(models.Model):
    @property
    def enabled_images(self):
        return self.images.filter(enabled=True)


class ProductImage(models.Model):
    product = models.ForeignKey(Product, models.PROTECT, related_name=""images"")
    enabled = models.BooleanField()
}}}

I want to eagerly load the `enabled_images` property so that it doesn't hit the database on access. So I write: `Product.objects.prefetch_related(Prefetch(""images"", ProductImage.objects.filter(enabled=True), to_attr=""enabled_images""))`. But that doesn't prefetch anything. The Prefetch is silently ignored.

The simplest workaround I can think of is:

{{{
class Product(models.Model):
    @property
    def enabled_images(self):
        try:
            return self.prefetched_enabled_images
        except AttributeError:
            return self.images.filter(enabled=True)
}}}

Then I can write `Product.objects.prefetch_related(Prefetch(""images"", ProductImage.objects.filter(enabled=True), to_attr=""prefetched_enabled_images""))` and now accessing `product.enabled_images` won't hit the database, but I think it's uglier."	Bug	new	Database layer (models, ORM)	6.0	Normal				Unreviewed	0	0	0	0	0	0