How to get post parameters from http request in lua sent to NodeMCU

Question

I sent this HTTP POST request via Tasker (Android app) to my NodeMCU, which looks like this:

POST / HTTP/1.1
Content-Type: application/x-www-form-urlencoded
User         


        

Answer 1

This function allows you to extract text from between two string delimiters:

function get_text (str, init, term)
   local _, start = string.find(str, init)
   local stop = string.find(str, term)
   local result = nil
   if _ and stop then
      result = string.sub(str, start + 1, stop - 1)
   end
   return result
end

Sample interaction:

> msg = "Play5"
> get_text(msg, "", "")
Play
> get_text(msg, "", "")
Play5

This is a modification of the above function that allows nil for either of the parameters init or term. If init is nil, then text is extracted up to the term delimiter. If term is nil, then text is extracted from after init to the end of the string.

function get_text (str, init, term)
   local _, start
   local stop = (term and string.find(str, term)) or 0
   local result = nil
   if init then
      _, start = string.find(str, init)
   else
      _, start = 1, 0
   end

   if _ and stop then
      result = string.sub(str, start + 1, stop - 1)
   end
   return result
end

Sample interaction:

> msg = "Play5"
> get_text(msg)
Play5
> get_text(msg, nil, '')
Play
> get_text(msg, '')
5
> get_text(msg, '', '')
Play