How do I check if a database table is devoid of entries? I could do this with Repo.all but I am already going down the rabbit hole and I am curious how do do it with Repo.one.
Repo.one(from x in App.Testbeds.Testbed, order_by: [desc: x.id], limit: 1)
Well, the most straightforward approach is to use Repo.exists?/2.
If it must be with Repo.one/2, then wrapping what you have with
is_nil would work (no need to specify an order in the query)
You should definitely use
exists. It will enforce a limit of 1 which is all you need to check existence.
Repo.one will fetch all entries and raise if more than one exists. So it is more expensive than you need.