Query with difficult conditions in the project using mptt

Question

I have some mptt model:

class Locations(MPTTModel):
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children')
    type = models.ForeignKey('LocationTypes')
    title = models.CharField(max_length=100)

Some models related with it:

class Building(models.Model):
    title = models.CharField(max_length=100)
    location = models.ForeignKey('Locations')

And QuerySet like this:

building_list = Building.objects.filter(title__icontains='house')

I know some "Location" "id", but not directly related to Building, one of ancestors. What better way to left in building_list, only those elements the is location one of descendants(not necessarily direct) of this "Location"?

Answer 1

You can get descendants list if you know location id with function get_descendants:

location = Location.objects.get(pk="some_location_id")
descendants = location.get_descendants().values_list('id', flat=True)
building_list = Building.objects.filter(title__icontains='house',
                                        location__in=descendants)