R Plumber Slack Bot Response

Question

I'm trying to create a bot response to slack using Plumber and I can get the model to work and get a text response when querying from the command line or testing from swagger. When I use a slash command from Slack though the response comes back but there is only an empty response displayed in the channel. I've tried a number of small tweaks but it just won't do it for me so hoping someone who has a working Slack Plumber bot can see what I'm doing wrong.

    #' return chatbot response
#' @param text the message used for analysis
#' @post /response
function(text=" ", res) {
  
  # turn parsed message into tidy dataframe
  msg_df <- tibble(line = 1:1, text = text)
  
  # unnest words in dataframe and create response
  msg_df <<- msg_df %>% unnest_tokens(word, text)
  body <- pred(msg_df)
  my_message <- list(response_type = unbox("in_channel"),
                     text=unbox(body))

  return(my_message)
}

and this is what I get back from slack once its dockerised and run.

the response coming back looks like this which is what I see in Slack tutorials

Response body

{
  "response_type": "in_channel",
  "text": "some text information"
}

Really appreciate any ideas!

Answer 1

An initial solution is that the Plumber serializer can be chaged to:

@serializer contentType list(type="text/plain") #provides a simple text response

This works if all you need is plain text without formatting (which works in my case)