Operating on an uploaded file - parsing

Question

I'm trying to parse an uploaded file as follows:
lib/thingy_web/controllers/things_controller.ex
def create(conn, %{"data" => %Plug.Upload{content_type: "application/octet-stream", filename: basename, path: dirname}}) do
things_params = dirname <> "/" <> basename
|> File.stream!
|> NimbleCSV.RFC4180.parse_stream
|> Enum.map(&AllThings.create_things_params/1)
|> Enum.map(&AllThings.create_things/1)
conn
|> put_status(:created)
end
However, when I try a POST with a test file:
curl -F 'data=#/root/test' http://localhost:4000/api/thing
I get the error:
[debug] Processing with ThingyWebWeb.ThingsController.create/2
Parameters: %{"data" => %Plug.Upload{content_type: "application/octet-stream", filename: "test", path: "/tmp/plug-1514/multipart-1514490176-65282591343221-1"}}
Pipelines: [:api]
[info] Sent 500 in 55ms
[error] #PID<0.544.0> running ThingyWeb.Endpoint terminated
Server: localhost:4000 (http)
Request: POST /api/thing
** (exit) an exception was raised:
** (File.Error) could not stream "/tmp/plug-1514/multipart-1514490176-65282591343221-1/test": not a directory
(elixir) lib/file/stream.ex:79: anonymous fn/2 in Enumerable.File.Stream.reduce/3
(elixir) lib/stream.ex:1270: anonymous fn/5 in Stream.resource/3
(elixir) lib/stream.ex:806: Stream.do_transform/8
Subsequent inspection of /tmp/plug-1514/ reveals that it is indeed an empty directory.
Is the uploaded file short-lived and can be configured to be long-lived, or am I missing something altogether here?

Answer 1

path contains the full path to the uploaded file. filename is just the name of the file that the user selected in the browser (or in this case, curl); the uploaded file is not stored with that name. You need to only pass the path to File.stream!/1:
things_params =
path
|> File.stream!
|> ...