Hi
I have a Product model that holds info common to all product types.
Product has a m2m categories field.
SimpleProduct and BundleProduct extends Product (one2one relation).
BundleProduct have a m2m products field (only SimpleProducts allowed).
class Product(models.Model):
> name=models.CharField()
> description=models.CharField()
> categories = models.ManyToManyField(Category)
>
> class SimpleProduct(Product):
> some_field=models.CharField()
>
> class BundleProduct(Product):
> products = models.ManyToManyField(Product)
>
When showing a list of products I'm making the following queries:
> products = Product.objects.filter(....)
> for p in products:
> for category in p.categories.all():
> ...
> if hasattr(p, 'bundleproduct'):
> for child in p.products.all():
> for category in child.categories.all():
>
This could end with a huge number of queries.
I can improve it with:
> Product.objects.filter(...).select_related('simpleproduct',
> 'bundleproduct')
>
I can further improve by using the select_reverse app for the m2m
categories field.
That's a big improvement but it can still end with a large number of queries
because each BundleProduct can have several products.
There are other product types like ConfigurableProduct. So a BundleProduct
can have a ConfigurableProduct child that has several SimpleProduct children
Is it possible to make a custom query that will fetch everything with a
single query and put it in a queryset so I can iterate it and work with it
as usual?
The docs about raw queries show simple use case. Is it possible to fetch
deep nested objects like products[1].categories.all()[2]
without making additional queries?
Thanks
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