Loading the xml2lua Library to Parse XML Data

Hi Guys,

Has anyone tried to parse XML data from an external device in a 5500AC2 using the xml2lua library?

I'm trying to figure out how to extract Dallas 1-Wire Temperature Sensor data from an XML data structure returned from the 1-Wire Gateway device I recently purchased. The gateway scans the 1-wire networks (up to 3) for sensors and then returns the data in a single XML structure, which seems to work well.

So far, I have been experimenting with writing Lua code on my MacBook using the ZeroBrane Studio IDE and the xml2lua package, and I am making progress.

Now, the challenge is to parse the data in the Lua code of my 5500AC2, but I need to load the xml2lua package somehow, which has multiple files and subfolders, and it's not apparent how to do it.

Any suggestions or alternative solutions to the problem of parsing XML data?

Regards
Alex Shepherd

 

I use the following script to download & parse xml, found at the lm forum.
Another simpler example https://forum.logicmachine.net/showthread.php?tid=5439&highlight=parse+xml

Code:

--[[
Download the BoM forecast for Melbourne
--]]

local logYesNo = false

-- Product ID from FTP Public Products and wanted location within the BoM file
local bomProduct = "IDV10450"
local location = "Melbourne"

function starttag(p, tag, attrs)
  if tag == 'area' and attrs.type == 'location' and attrs.description == location then
    in_area = true
  elseif tag == 'forecast-period' and in_area then
    index = tonumber(attrs.index)

    if index then
      forecast[index] = {}
    end
  elseif index then
    prop = attrs.type
  end
end

function endtag(p, tag)
  if tag == 'area' then
    in_area = false
  elseif tag == 'forecast-period' then
    index = nil
  elseif index then
    prop = nil
  end
end

function text(p, txt)
  if in_area and index and prop then
    forecast[index][prop] = txt:trim()
  end
end

-- download the bom forecast file
local uri = "ftp://ftp.bom.gov.au/anon/gen/fwo/"..bomProduct..".xml"
require('socket.ftp')
local data, err = socket.ftp.get(uri)

if data and not err then
  forecast = {}

    require('lxp').new({
      StartElement = starttag,
      EndElement = endtag,
      CharacterData = text,
    }):parse(data)

    logger(logYesNo, 'Forecast tree', forecast)
 
  if forecast[0] then
    -- the forecast max for today is not always present in the file
    if forecast[0].air_temperature_maximum then
      local forecastTempMax = tonumber(forecast[0].air_temperature_maximum)
            -- do stuff
    end
  else
    logger(logYesNo, 'Forecast not found in data', data)
  end
else
  logger(logYesNo, 'No data from '..uri, err)
end

 

Ah huh - thanks @SgrAystar.

So is the Lua "lxp" package already installed and part of the Lua environment in the 5500AC2?

 

Yes. My 5500AC2 is currently on firmware 2.1.0 but this script has been running for a couple of years on earler releases.

 

Awesome, thanks for the assistance.
My requirement should be able to be done using a similar approach.

Alex