httr2 multipart body with unnames list elements does not accept unnamed list

[laurens]

I am currently writing an r package so that one can send signal text messages from R.
I am planning to make this open source.
It is based on the rest specification from GitHub - bbernhard/signal-cli-rest-api: Dockerized Signal Messenger REST API

Sofar I have been using httr2 to make the rest calls and this works very well as long as I don't include attachments.

for example the following curl command works very well as follows:

`curl -X POST -H "Content-Type: application/json" -d '{"message": "Hello World!", "number": 
"+431212131491291", "recipients": ["+4354546464654", "+4912812812121"]}' 'http://127.0.0.1:8080/v2/send'`

Request_url <- "http://127.0.0.1:8080/v2/send"

Request_body <-  list( 'message' = "Hello World!"
                                             , 'number' =  "+431212131491291"
                                             , "recipients" = list("+4354546464654", "+4912812812121")
                                             )

query <- httr2::request(base_url = Request_url) |>
               httr2::req_headers('Content-Type' = 'application/json') |>
               httr2::req_timeout(60) |>
               httr2::req_body_json(body)|>
               httr2::req_perform()

 query
<httr2_response>
POST http://127.0.0.1:8080/v2/send
Status: 201 Created
Content-Type: application/json
Body: In memory (29 bytes)

and I also receive the message in Signal.

However if I try to add an attachment it suddenly does not want to work anymore.
The curl specification is as follows:

curl -X POST -H "Content-Type: application/json" -d '{"message": "<message>", "base64_attachments": ["<base64 encoded attachment>"], "number": "<number>", "recipients": ["<recipient1>", "<recipient2>"]}' 'http://127.0.0.1:8080/v2/send'

as it can observed the recipients are required as a list without named list elements:

However if I change my code than as follows:

base64_attachments <- "C:\\somefile.pdf"

 query <- httr2::request(base_url = Request_url) |>
               httr2::req_headers('Content-Type' = 'application/json') |>
               httr2::req_user_agent("RSignalApi") |>
               httr2::req_timeout(60) |>
               httr2::req_body_json(Request_body ) |>
               httr2::req_body_multipart(base64_attachments = curl::form_file(base64_attachments))|>
               httr2::req_dry_run()

I then get the following error:

Error in curl::handle_setform(handle, .list = req$fields) : 
  Unsupported value type for form field 'recipients'.
Called from: curl::handle_setform(handle, .list = req$fields)

if I only use one recipient as character (so not a list anymore) I get the following error:

Error in `httr2::req_perform()` at package/R/hello.R:53:7:
! HTTP 400 Bad Request.

Meaning that the rest server really expects the unnamed list for receipients.

Does somebody have any advice how to tackle this?

[margusl]

I'm afraid you can't mix req_body_json() & req_body_multipart() like this. Besides, from curl example, it doesn't look like a multipart request, just a base64-coded content in JSON payload.
I'd try with something like this:

base64_attachments <- "foo.txt"
Request_url <- "http://127.0.0.1:8080/v2/send"
Request_body <- list(
  message            = "Hello World!",
  base64_attachments = list(base64enc::base64encode(base64_attachments)),
  number             = "+431212131491291",
  recipients         = list("+4354546464654", "+4912812812121")
)

httr2::request(base_url = Request_url) |>
  httr2::req_headers('Content-Type' = 'application/json') |>
  httr2::req_user_agent("RSignalApi") |>
  httr2::req_timeout(60) |>
  httr2::req_body_json(Request_body ) |>
  httr2::req_dry_run()
#> POST /v2/send HTTP/1.1
#> Host: 127.0.0.1:8080
#> User-Agent: RSignalApi
#> Accept: */*
#> Accept-Encoding: deflate, gzip
#> Content-Type: application/json
#> Content-Length: 137
#> 
#> {"message":"Hello World!","base64_attachments":["YmFyDQo="],"number":"+431212131491291","recipients":["+4354546464654","+4912812812121"]}

^{Created on 2024-03-17 with reprex v2.1.0}