Rails Console - Delete all records that don't have any associations

Question

So, I have a Model House , and a house can have_many Room s.

I would like to delete all records of House that have no Room s.

I've tried

House.includes(:room).having('room.id IS NULL')

which errors, as does

House.all().where(:room.count == 0)

and many other things that I've tried along the same lines.

I'm probably missing something really straightforward, anyone have any ideas?

Answer 1

The association should be plural

House.includes(:rooms).where(rooms: { id: nil }).count

And you should be able to delete them using

ids = House.includes(:rooms).where(rooms: { id: nil }).pluck(:id)
House.where(id: ids).delete_all

# Note: I'm leaving this as reference. It seems to raise an error.
# House.includes(:rooms).where(rooms: { id: nil }).delete_all

Otherwise you can work with a little bit of pure SQL and perform a DELETE statement directly using a join .

Answer 2

House.includes(:rooms).where('rooms.id IS NULL')