Django. Annotate wtih Count parameter doesn't work

Question

I have 2 models:

class Parameter(models.Model):
    name = models.CharField('Название', max_length=50)


class ProductParameter(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE, verbose_name='Продукт', related_name='parameters')
    parameter = models.ForeignKey(
        'Parameter',
        on_delete=models.CASCADE,
        verbose_name='Параметр',
        related_name='product_parameters'
    )

I do the queryset for getting all parameters that has more than 1 ProductParameter:

parameters = Parameter.objects.annotate(
    count=Count('product_parameters')
).exclude(count__lte=1)

But that's not working. When a parameter obj has 2 ProductParameter objects, the count equals to 1.
When I use the expression below, all works:

parameters = [param for param in Parameter.objects.all() if param.product_parameters.count() > 1]

Where is my error?

Eric Svitok · Accepted Answer · 2020-07-16 13:29:11Z

1

Maybe using count as the field name is the issue. Try renaming it or omitting it to use the defaulted field name.

parameters = Parameter.objects.annotate(Count('product_parameters')
).exclude(product_parameters__count__lte=1)

answered Jul 16, 2020 at 13:29

Eric Svitok

8426 silver badges12 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Django. Annotate wtih Count parameter doesn't work

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related