Question

I have the following query:

Child.objects.filter(
    foreign_key_field__in=Parent.objects.filter(param=something))

The view dies with:

invalid literal for int() with base 10: 'value of something'

It seems to me that the foreign_key_field expects an id of some kind, and I’m giving it an actual value. Am I doing something wrong? Is this possible?

The goal is to avoid iterating over the child_set of the parent to call another query-generating method in the child, which causes a query to be generated for each and every single object returned. Instead, I want to induce the ORM to grab all the matching children in one query, and iterate over them as normally.

Answer 1

The question is are you doing:

Child.objects.filter(parent__in=Parent.objects.filter(...))

or

Child.objects.filter(parent_id__in=Parent.objects.filter(...))

The first version will work, the second version will give you the “invalid literal for int() with base 10” error.