Can't access file/file path in changeset about arc_ecto HOT 2 OPEN

I believe this is pretty much not directly related to the arc_ecto. Handling uploads with directly with Plug.Upload will give the desired flexibility to manipulate resources before pushing them to S3.

from arc_ecto.

@pejrich if you want custom paths, you need to work on your uploader file and override storage_dir function. Unfortunately you can't use the model's id because it's not available when you create a new record (except the case you're adding a file after the record is already created).
If you need to apply some algorithm to generate the desired path, then you have to work on the changeset before cast_attachments is called.

from arc_ecto.