How can I check what objects will be cascade deleted in Django?

Question

In the /admin/ section of Django you can choose to delete items.

If any related objects would be deleted along with your chosen object you get to see a list of affected objects before you confirm delete.

Can I check this in my own function programmatically?

I'd like to do something like

for item in Item.objects.all():
    if not deletion_would_also_delete_other_objects(item):
        item.delete()

Answer 1

Could you use from django.db.models.deletion import Collector to do this?

from django.db.models.deletion import Collector
from .models import Item
  
for item in Item.objects.all(): 
    collector = Collector(using='default')
    collector.collect([item])

    # dependencies should be an empty dict if the item is not related to anything
    if not collector.dependencies:
        item.delete()

Answer 2

I suggest using the NestedObjects util provided in django admin.

from django.contrib.admin.utils import NestedObjects
from django.db import router

using = router.db_for_write(Item._meta.model)
# if you only have one database, just set using = "default"

nested_object = NestedObjects(using)
nested_object.collect([Item])
# If you want to delete multi item, you can use:
# nested_object.collect(Model.objects.filter(type="deleted"))

print(nested_object.nested()

The result look like this: