Making DB calls with Ecto Multi `run` sections

Questions / Help
1

Hi

With Ecto Multi, when making DB calls within a run, do you need to use the repo function argument or is that provided purely as a convience?

eg.

Multi.new()
|> Multi.run(:customer, fn _repo, %{connection: connection} ->
  FooBars.create_or_update_foobar(foobar_attrs)
end)
|> Repo.transaction()

Thanks

Josh

2

It’s a convenience for allowing those callbacks to be better abstractable in case you have many repos.

3

There are projects that have more than one repo. And in rare cases you might even use Ecto.Multi with the multiple repos in a single “transaction” (though that’s not trivial to pull off well because it’s not technically a single DB transaction as it can span multiple DBs).

1 Like
4

Thanks for the quick replies @LostKobrakai and @dimitarvp, and the explanations.