How can I retrieve data from the request body sent to a Plumber API?

The answer below could probably help you understand plumber parsers?

A solution similar to this?

#* Process two files in the request body
#* @post /process_files
#* @param files:[file]
#* @parser multi
#* @parser csv
function(files, req, res) {

      if (length(files) < 2) {
        res$status <- 400
        res$body <- '{"error": "Two files must be included in the request."}'
        return()
      }
    
      file1 <- files[[1]]
      file2 <- files[[2]]

  ## here I  process the data 

  res$status <- 200
  res$body <- '{"message": "Files processed successfully."}'
}