R translating curl commands to post multipart form - problem - r

Question

I have the following curl command that, when run from command line, works perfectly:
curl -X POST -u "myusername|myemail#domain.com:myPassword"
-H "Content-Type: multipart/form-data"
--form file=#MyFileForUploading.csv
https://mysite-data.herokuapp.com/api/mymarket/setups/uploads
[Apologies: this is not a working example as I cannot provide the real url and credentials. I am hoping you can help me with the translation from curl to httr without running the example yourselves.]
Here's my attempt to translate the above to the language of R's httr, which did NOT work:
library(httr)
POST("https://mysite-data.herokuapp.com/api/mymarket/setups/uploads",
config = authenticate("myusername|myemail#domain.com", "myPassword"),
body = upload_file("MyFileForUploading.csv", type = "text/csv"),
encode = "multipart")
The curl command serves to upload a csv file being used as setup for a web-based trading interface. Setup includes things like trader initial holdings of objects, trader permissions (to buy and sell), etc. All this is simply stored as a csv file (columns = setup parameters; rows = traders).
Can anyone see an obvious mis-translation? I am very ignorant about both curl and httr. My translation is based on learning from examples and I wouldn't be surprised if there's an obvious failure, for example, with the content-type part of the command.
Thanks!

Answer 1

You're really close. This works with environment values setup in "~/Renviron":
library("httr")
post_url <- Sys.getenv("POST_URL")
username <- Sys.getenv("USERNAME")
password <- Sys.getenv("PASSWORD")
csv_file <- Sys.getenv("CSV_FILE")
POST(
url = post_url,
config = authenticate(username, password),
body = list(file = upload_file(csv_file)),
encode = "multipart",
verbose()
) -> response
The key is the file = as you used in your CURL command.