django query with values(), not fetching get_absolute_url

Using Django Forms & APIs
1

Hi, I tried the following query and I got the get_absolute_url and a human readable version of a choice field in my django template (get_FOO_diplay) working correctly ,

def get_queryset(self):
        return Task.objects.filter(status='c') \ 
            .select_related('created_by', 'boat', 'assigned_to').all()

However when use the same query with values(), neither my get_absolute_url or get_FOO_diplay seems to work correctly, following is my query:

def get_queryset(self):
        return Task.objects.filter(status='c') \
            .select_related('created_by', 'boat', 'assigned_to') \
                .values('created_by__username','boat__name','name', 'status', 'created_date')

Note: the status is the choice field,
can anyone point out what I am doing wrong here.

thanks.

2

.values will return a dictionary, not the model instance. So you won’t be able to use functions from it.

3

To amplify @fabtjar 's answer a little, and assuming you’re using CBVs, the get_queryset function is supposed to return a queryset (values doesn’t).
Review the docs at QuerySet API reference | Django documentation | Django to see what functions return querysets and which don’t. You shouldn’t be using any function on your query that doesn’t return a queryset in that method.

4

I cannot acces any methods inside my model class, if I use value() function right. think i’ll need to experiment with other querset apis. Thanks

5

Side note: Not just the values function. You can’t chain any function that doesn’t return a queryset as listed in the referenced docs.

It would perhaps be more instructive to understand why you think you need (or want) to use values at that location.

6

I’m thinking of reducing my queries. Right now my queryset is getting more information than I need, since few related table are included.

For the moment, only the values() function is querying the desired result. However I am reading through the docs to figure it out. Thanks

7

Unless you can demonstrate an actual “problem” with this, supported by metrics, I suggest you not worry about it.

In the general case:

  • You’ve probably spent more time thinking about this issue than you will ever save over the life of your project.
  • By definition, get_queryset is supposed to return a queryset, not a list.
  • Keeping it as a queryset makes other changes easier going forward. Should you ever change your view, you won’t need to go back and change your get_queryset method.
1 Like
8

Thanks very much, will take that to consideration.