it does blow up with a bang.. so a bit more defensive code is needed, unless you are doing bangs on purpose..
if you simply remove the bang and use get_by it will return nil on not found, and that will be cached - depending on your caching strategy you might not want that - and you can use the ignore feature.. that way the nil/not found is not cached and the db is always queried on slugs that are not found - but it all depends..
here is an example.. using :ignore so the nil is not cached.. else just remove the bang in get_by
def get_cached_thing!(slug) do
Cachex.get(
:my_cache,
slug,
fallback: fn slug ->
case result = Repo.get_by(Mything, id: slug) do
%Mything{} ->
# happy path - commit to cache
{:commit, result}
nil ->
# not found - ignore tuple so it's not cached
{:ignore, nil}
end
end
)
|> case do
# It's not common to return error strings, rather you'd probably want an error tuple
{:error, _} ->
{:error, "error - devops needed?"}
# the ignore returns an :loaded tuple - so match nil
{:loaded, nil} ->
{:error, :not_found}
{success, result} when success in [:ok, :loaded] ->
{:ok, result}
end
end
