Python Django Rest Framework UnorderedObjectListWarning

Question

I upgraded from Django 1.10.4 to 1.11.1 and all of a sudden I'm getting a ton of these messages when I run my tests:

lib/python3.5/site-packages/rest_framework/pagination.py:208:
UnorderedObjectListWarning: 
Pagination may yield inconsistent results with an unordered object_list: 
<QuerySet [<Group: Requester>]>
paginator = self.django_paginator_class(queryset, page_size)

I've traced that back to the Django Pagination module: https://github.com/django/django/blob/master/django/core/paginator.py#L100

It seems to be related to my queryset code:

return get_user_model().objects.filter(id=self.request.user.id)

How can I find more details on this warning? It seems to be that I need to add a order_by(id) on the end of every filter, but I can't seem to find which code needs the order_by added (because the warning doesn't return a stack trace and so it happens randomly during my test run).

Thanks!

Edit:

So by using @KlausD. verbosity tip, I looked at a test causing this error:

response = self.client.get('/api/orders/')

This goes to OrderViewSet but none of the things in get_queryset cause it and nothing in serializer class causes it. I have other tests that use the same code to get /api/orders and those don't cause it.... What does DRF do after get_queryset?

https://github.com/encode/django-rest-framework/blob/master/rest_framework/pagination.py#L166

If I put a traceback into pagination then I get a whole bunch of stuff related to django rest framework but nothing that points back to which of my queries is triggering the order warning.

Usually it should be easy to find by the name of the test that causes the warning. You might want to run tests with verbosity (-v 2 on most test runners) — Klaus D.
– Klaus D., Commented May 17, 2017 at 19:59
Looks for queries where you are doing an offset and limit but no order_by — gipsy
– gipsy, Commented May 17, 2017 at 20:14

starball · Accepted Answer · 2022-12-23 08:46:55Z

211

So in order to fix this I had to find all of the all, offset, filter, and limit clauses and add a order_by clause to them. Some I fixed by adding a default ordering:

class Meta:
   ordering = ['-id']

In the ViewSets for Django Rest Framework (app/apiviews.py) I had to update all of the get_queryset methods as adding a default ordering didn't seem to work.

edited Dec 23, 2022 at 8:46

starball♦

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answered May 17, 2017 at 23:45

Denise Mauldin

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7 Comments

Amir Savand Over a year ago

Awesome, didn't know that DRF reads the model for ordering too <3

Ariel Over a year ago

I do have a default ordering in my model but I still get this warning :|

Ariel Over a year ago

My mistake. I had ordering in the parent class, but I was overriding the Meta attribute without properly subclassing it as described in the docs, and in the child class' Meta I had no ordering, so the value from the parent was lost.

Lord Elrond Over a year ago

Note that adding the - in ordering = ['-id'] orders your query in descending order.

Michael Aquilina Over a year ago

I think the correct solution is actually not to specify a default ordering on the model because this can have severe side effects in the future for anything else that happens to use this model. An example of a side effect that might come back to haunt you is the query planner deciding to use the incorrect index to priortise ordering instead of filtering. This can have huge performance implications on larger tables. Instead you should specify the default ordering on your drf view or specifically in the author's case, the query you are returning should specify an order_by().

|

Rajiv Sharma · Accepted Answer · 2017-09-11 04:32:26Z

74

I was getting this warning when i used objects.all() in my view.py

profile_list = Profile.objects.all()
paginator = Paginator(profile_list, 25)

to fix this i changed my code to :

profile_list = Profile.objects.get_queryset().order_by('id')
paginator = Paginator(profile_list, 25)

answered Sep 11, 2017 at 4:32

Rajiv Sharma

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1 Comment

radtek Over a year ago

I think it should be Profile.objects.all().order_by('id') .. at least that works for me, otherwise I get AttributeError: type object 'Profile' has no attribute 'get_queryset'

Paul Schreiber · Accepted Answer · 2021-10-22 19:17:56Z

21

In my case, I had to add order_by('id') instead of ordering.

class IntakeCaseViewSet(viewsets.ModelViewSet):
    schema = None
    queryset = IntakeCase.objects.all().order_by('id')

Ordering needs to be in the model using Class Meta (not View).

edited Oct 22, 2021 at 19:17

answered Oct 7, 2020 at 16:08

Paul Schreiber

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Comments

AlanSE · Accepted Answer · 2019-05-03 13:15:30Z

Let me give an answer updated to new developments...

https://code.djangoproject.com/ticket/6089

The default ordering of the User model has been removed in Django. If you found yourself at this page because of an upgrade, it's very likely connected to this change.

There are 2 versions of this problem you might be dealing with.

your own model does not have a default ordering in its Meta (see accepted answer)
you are using a model from an app you are using as a dependency which does not have a default ordering

Since literally the Django User model itself does not adhere to ordering, it's very clear that the second scenario cannot be resolved by asking the maintainers of those dependencies to put in a default ordering. Okay, so now you either have to override the model being used for whatever your doing (sometimes a good idea, but not good for addressing such a minor issue).

So you're left with addressing it on the view level. You also want to do something that will play nicely with any ordering filter class you have applied. For that, set the view's ordering parameter.

class Reviewers(ListView):
    model = User
    paginate_by = 50
    ordering = ['username']

Also see Is there Django List View model sort?

Michael Benin · Accepted Answer · 2018-07-04 18:42:53Z

5

Another option is to add OrderingFilter

http://www.django-rest-framework.org/api-guide/filtering/#orderingfilter

answered Jul 4, 2018 at 18:42

Michael Benin

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Comments

therealak12 · Accepted Answer · 2020-04-19 07:59:44Z

2

Including this didn't work for me.

class Meta:
   ordering = ['-id']

But changing get_queryset(self) and sorting the list with .order_by('id') did. Maybe worked because I'm using filters, I don't know

class MyView(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializerSerializer

    def get_queryset(self):
        user = self.request.user
        return MyModel.objects.filter(owner=user).order_by('id')

edited Apr 19, 2020 at 7:59

therealak12

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answered Aug 2, 2019 at 14:36

Malinoski

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Comments

Ahmed Shehab · Accepted Answer · 2020-09-21 00:05:07Z

1

Update the model meta class instead.

class UsefulModel(models.Model):
    
    class Meta:
        ordering='-created' # for example

you can still override the ordering from the view attribute 'ordering' As advised by AlanSE previously.

class UsefulView(ListView):
    ordering = ['-created']

edited Sep 21, 2020 at 0:05

answered Aug 13, 2020 at 21:29

Ahmed Shehab

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Comments

SanRaph · Accepted Answer · 2021-07-08 08:33:31Z

0

In my case, it expected a tuple and that tuple has to contain a comma even when you are parsing just an item in it.

     class Meta:
      ordering = ('-name',)

answered Jul 8, 2021 at 8:33

SanRaph

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