I got the error mentioned in the title while running the following code. The weird part is I did get the response I expected but with this message attached.

defmodule Kodi.Worker do
def get_response() do
    result = url_for() |> HTTPoison.get |> parse_response
    case result do
        {:ok, response} -> "response: #{response}"
        :error -> "query error"
    end
end

defp url_for() do
    "http://192.168.0.104:8080/jsonrpc?request={%22jsonrpc%22:%20%222.0%22,%20%22id%22:%201,%20%22method%22:%20%22Playlist.GetPlaylists%22}"
end

defp parse_response({:ok, %HTTPoison.Response{body: body, status_code: 200}}) do
    body |> JSON.decode! |> filter_response
end

defp parse_response(_) do
    :error
end

defp filter_response(json) do
    try do
        #response = (json["result"])
        #{:ok, response}
        {:ok, json}
    rescue
        _ -> :error
    end
end
end

Any idea?

EDIT:
Error message:
** (Protocol.UndefinedError) protocol String.Chars not implemented for %HTTPoison.Response{body: “{"id":1,"jsonrpc":"2.0","result":[{"playlistid":0,"type":"audio"},{"playlistid":1,"type":"video"},{"playlistid":2,"type":"picture"}]}”, headers: [{“Content-Length”, “133”}, {“Content-Type”, “application/json”}, {“Date”, “Wed, 04 May 2016 05:00:55 GMT”}], status_code: 200}
(elixir) lib/string/chars.ex:3: String.Chars.impl_for!/1
(elixir) lib/string/chars.ex:17: String.Chars.to_string/1
(kodi) lib/worker.ex:5: Kodi.Worker.get_response/0

It looks like you are correct. I might be treating the response as string when it’s not. I will look into it again to figure out how to fix it. Thanks.

I made a mistake in my code. I am fixing it and update the thread “soon”.