The model(the pk/id is auto generated)
class Comments(models.Model): parent = models.ForeignKey(to="self", null=True)
And the SQL query
SELECT * FROM comments WHERE ( parent_id IN ( 1, 2, 3, 4 ) AND ( SELECT COUNT(*) FROM comments AS f WHERE ( f.parent_id = comments.parent_id AND f.id <= comments.id ) )<= 2 )
Answers:
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Method 1
We can determine the count with the help of a Subquery
:
from django.db.models import Count, OuterRef, Q, Subquery, Value from django.db.models.functions import Coalesce Comments.objects.filter( parent_id__in=[1,2,3,4] ).annotate( ncomment=<strong>Coalesce(Subquery(</strong> Comments.objects.filter( parent_id=OuterRef('pk'), pk__lte=OuterRef('pk') ).values('parent_id').annotate( ncomment=Count('pk') ).values('ncomment').order_by('parent_id') ), Value(0)) ).filter( ncomment__lte=2 )
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