python - Filter queryset by reverse exists check in Django -

i have models:

class post(models.model):     content = models.charfield()     user = models.foreignkey('users.user')     active = models.booleanfield(default=true)  class comment(models.model):     post = models.foreignkey(post, related_name='post_comments') 

and queryset filtered query params:

user = request.query_params.get('user_id', none) active = request.query_params.get('active', none) has_comments = request.query_params.get('has_comments', none)  qs = post.objects.all()  if user:     qs = qs.filter(user=user) if active:     qs = qs.filter(active=active) if has_comments:     ??? 

i don't how can filter query while maintaining previous filters. possible?

according documentation:

to refer “reverse” relationship, use lowercase name of model.

from this answer follows code be:

if user:     qs = qs.filter(user=user) if active:     qs = qs.filter(active=active) if has_comments:     qs = qs.filter(comment__isnull=false) 

with regards performance take this answer account:

django doesn't support select_related() method reverse foreign key lookups, best can without leaving python 2 database queries.

you should have @ prefetch_related can, unlike select_related lookups across reverse foreignkeys, albeit separate query each element of queryset.