CODEWITHSUNDEEP
djangodjango-orm
Compadre
Compadre

Reputation: 834

Confusion with Queryset.annotate()

I have two models:

class Property(models.Model):
    # code here...

class AccommodationType(models.Model):
    property = models.ForeignKey(Property, related_name='accommodation_types')
    # rest of code here...

What I'm trying to to is to annotate Property's queryset with count of related AccommodationType's and filter it by the value of this count. So here is my code:

qs = Property.objects.all()
qs.annotate(acc_types_count=Count('accommodation_types'))
filtered = qs.filter(acc_types_count=1)

and here I got the error:

django.core.exceptions.FieldError: Cannot resolve keyword 'acc_types_count' into field. Choices are:  # ...rest of the fields

Where I am wrong?

Upvotes: 0

Views: 454

Answers (1)

Daniel Roseman
Daniel Roseman

Reputation: 599778

annotate, like filter, doesn't mutate the queryset but returns a new one. You need to reassign that to qs:

qs.annotate(acc_types_count=Count('accommodation_types'))

Or combine it with the original query:

qs = Property.objects.all().annotate(acc_types_count=Count('accommodation_types'))

Upvotes: 1

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