Django objects.filter vs objects.all

Question

I have a question regarding the filter() and all() methods of django objects. It is not a question which one of the two is preferred, I just noticed an odd (to me) behavior. Because, as it is laid out in

Django ORM - objects.filter() vs. objects.all().filter() - which one is preferred?

in Django src, both ways should return the same (they both reference the chain() method):

See:

https://github.com/django/django/blob/0963f184abd96800b76b19a6a181e1b544c7fafe/django/db/models/query.py#L928

And:

https://github.com/django/django/blob/0963f184abd96800b76b19a6a181e1b544c7fafe/django/db/models/query.py#L951

So the filter() and all() method should return the same objects. But I recently discovered the following behavior:

MyModel.objects.all()[0].update(name="Test")

# --> $: AttributeError: type object 'MyModel' has no attribute 'update'

# And to check if it indeed has no update method:

MyModel.objects.all[0].__dir__() # --> no update() method in returned dictionary but a save method

So while above code raises Error, line below would work:

MyModel.objects.all()[0].name = "Test"
MyModel.objects.all()[0].save()

However, if the same object is retrieved by the filter() method, it has the update() method.

Why do I get the same object both times but with seemingly different methods added to it?

Answer 1

the update() function is only on the Manager object. Looking at your comments, you are effectively called MyModel.objects.filter(name="Test").update(name="test2") which is a valid queryset function. If you used MyModel.objects.get(name="Test") which would be the same as the all() version.

In your all() example, you are working on the model, which lacks an update() function.