Plumber does not find request body - r

Question

I am currently writing a webhook on a heroku server and for some reason I am having difficulty obtaining the values stored in the body of the request as it always seems to turn up as NULL. My app.R script looks like all those in the guides:
#app.R
library(plumber)
library(tidyverse)
port <- Sys.getenv('PORT')
pr <- plumb("plumber.R")
pr$run(
host = '0.0.0.0',
port = as.numeric(port)
)
My plumber.R file starts like this.
library(plumber)
library(tidyverse)
#* Log some information about the incoming request
#* #filter logger
function(req){
print('LOGGER')
print( req)
cat(as.character(Sys.time()), "-",
req$REQUEST_METHOD, req$PATH_INFO, "-",
req$HTTP_USER_AGENT, "#", req$REMOTE_ADDR, "\n")
plumber::forward()
}
#* #filter bodyExists?
function(req, res){
print( 'BODY FILTER')
print( req$body)
if (is.null(req$body)){
res$status <- 404
return(list(error="Body not found"))
} else {
plumber::forward()
}
}
Every time it receives a request the console shows out this:
And stops because there is no body. I have tried sending it requests from multiple sources where I know a body is being sent with the request but for some reason plumber does not find it when it reaches my api. I have been following using https://github.com/virtualstaticvoid/heroku-plumber-app as a template and I don't see what Im doing different from them.

Answer 1

Was supposed to use req$postBody rather than req$body

Answer 2

Plumber should be able to parse the body of the post request automatically unless the content type is incorrect or unspecified.
In my case, I had forgotten to specify the content type header of the request (I tested the API using curl from the command line). Once I set it to -H "Content-Type: application/json", plumber was able to parse the body correctly and I could see the payload in req$body as well as req$args.
If you decide to use req$postBody, like the OP did, note that as of plumber v1.0.0 it is recommended to use req$bodyRaw rather than req$postBody. For more information, see postBody in the plumber request object as well as plumber PR#665.