Writing Curl POST in R: uploading an image to a website - r

Question

I am trying to upload an image to a website. Below is the successful curl function:
curl --location --request POST 'http://xxxxx?laboratoryResultVisibleId=LR-116807&assayAttribute=Trace&onBehalfOf=minnie' \
--header 'Authorization: Basic U1JWR0JMLUdEQklPTDpQZjgyNTE5Mw==' \
--form 'imageFile=#/C:/Users/minnie/Downloads/plot.png'
I am writing my R code as follows:
username <- "minnie"
url <- "http://xxxxx"
auth <- authenticate(user='abc', password='xyz', type="basic")
header <- list(username)
names(header) <- "X-On-Behalf-Of"
filepath <- "C:/Users/minnie/Downloads/plot.png"
post_zip <- httr::POST(
url = url,
auth,
body = list(
laboratoryResultVisibleId = 'LR-116807',
assayAttribute = 'Trace',
file = httr::upload_file(filepath),
userid = username
),
httr::add_headers("Content-Type"="multipart/form-data")
)
post_zip
content(post_zip, "text")
and I got the following feedback:
Response [http://xxxxx]
Date: 2020-11-18 22:30
Status: 200
Content-Type: application/json;charset=UTF-8
Size: 43 B
> content(post_zip, "text")
[1] "{\"success\":false,\"message\":\"No File found\"}"
It seems that no file has been found. Any clue? Thank you so much for your help :-)

Answer 1

I feel like this has something to do with http vs https, can you try changing to https?

Answer 2

The problem resides in the file path. We should use the file.path () function in R to let the server know it is a file path, rather than a character string.
filepath <- file.path(getwd(), "plot.png")
post_zip <- httr::POST(
url = url,
auth,
body = list(
laboratoryResultVisibleId = 'LR-116807',
assayAttribute = 'Trace',
imageFile = httr::upload_file(filepath),
userid = username
),
httr::add_headers("Content-Type"="multipart/form-data")
)
post_zip
content(post_zip, "text")