'dict' object has not attribute 'pk' when using Django bulk_update()

Question

I have the following code:

obj = Products.objects.filter(dump__product_name = 'ABC, dump__product_color = 'black').values()
new_price = [100, 200, 300]

for item in range(len(obj)):
   obj[item]['price'] -= new_price[item]

Products.objects.filter(dump__product_name = 'ABC, dump__product_color = 'black').bulk_update(obj, ['price'])

But I am getting the error, Exception inside application: 'dict' has no attribute 'pk'

The value of obj looks like this:

<QuerySet [{'id': 1, 'product_name': 'Acer - Laptop', 'price': 350}, 
           {'id': 1, 'product_name': 'Dell - Laptop', 'price': 450}, 
           {'id': 1, 'product_name': 'Samsung- Laptop', 'price': 650}]>

I am unable to figure out what's wrong with the code. Any help would be much appreciated. Thanks a lot in advance

See for example https://www.django-antipatterns.com/antipattern/over-use-of-values.html — Willem Van Onsem, Jun 10 '21 at 14:11

blhsing · Answer 1 · 2021-06-10T14:12:38.637

The QuerySet.values method returns a sequence of dicts, but QuerySet.bulk_update takes a sequence of model instances, not dicts. You should iterate over the QuerySet returned by the filter method for a sequence of model instances that you can make changes to instead, and you also don't have to filter again when you perform bulk_update because it's performed on instances of specific primary keys:

items = list(Products.objects.filter(dump__product_name='ABC', dump__product_color='black'))
new_prices = [100, 200, 300]

for item, new_price in zip(items, new_prices):
   item.price -= new_price

Products.objects.bulk_update(items, ['price'])

There is pretty much only one good way to do this after all. ;-) — blhsing, Jun 10 '21 at 14:11

score 1 · Answer 2 · answered Jun 10 '21 at 14:10

You should not use .values() since that will create dictionaries instead of model objects, and thus does not offer all the functionality the model provides.

You can work with:

obj = list(Products.objects.filter(
    dump__product_name = 'ABC', dump__product_color = 'black'
))
new_price = [100, 200, 300]

for item, prc in zip(obj, new_price):
   item.price -= prc

Products.objects.bulk_update(obj, ['price'])

'dict' object has not attribute 'pk' when using Django bulk_update()

2 Answers2