Order a Django queryset in ascending order but with 0-valued items at the end

Question

I am new to python, django. What I am trying to do is that I have a model defined as products which has two columns: name and price.

name    price
pen      20
paper    30
eraser   0

I am trying to sort them using the following code:

Product.objects.all().order_by('-price')

This sorts the values as 0,20,30.

The model code is

class Product(models.Model):
    name = models.CharField(max_length=100, blank=True, null=True)
    price = models.IntegerField('Price', blank=True, null=True)

What I am trying to achieve is to sort it as 20,30,0 with 0 being appended at the end.

Is there any function with which I can achieve it?

Answer 1

You could order by a calculated value in case you really want to do everything on the DB level. This should work:

Product.objects.all().order_by(\
        Case(When(price=0, then=Value(MAX_INT)), default=F('price')))

Where MAX_INT=2147483647 is the value of a 32 bit signed integer which is safe on all Django-supported DBs.

Answer 2

The following could work, it's not the nicest code to implement but for your special case I think this is the easy way to do it using queryset directly, otherwise you can think about implementing it in Python(sorted or other builtin functions)

qs = Product.objects.exclude(price=0).order_by('-price') | Product.objects.filter(price=0)