Django update table using data from another table

Question

I have 2 tables products and catagories connected by foreign key. I need to update field products.new_cost using field catagorie

Answer 1

You cannot use F, but you can use Subquery and OuterRef:

from django.db.models import Subquery, OuterRef

cost = Category.objects.filter(
    id=OuterRef('category_id')
).values_list(
    'price_markup'
)[:1]

Product.objects.update(
    new_cost=Subquery(cost)
)