Strategy/Advice to pass Lua table to AJAX?

[Agonostis]

Hi,

I'm really liking using AJAX + Girder to make my interfaces. I've got the web-page --> girder event triggering working great - it's super-responsive over my home network, and not half bad over the 'net.

Now I'm ready to make more progress on the girder--->web direction. I've pored through the examples that ship with Girder and I think I understand how it works.

I'd really like to write a function whose argument is a Lua table (for example, a weather.Local.cc object) that will return XML, comma-separated text, or anything else useful to pass back to the XMLhttpRequest object for use in my webpage.

Kind of like a combination of the GetField() (in the ajax_req.lhtml example) and table.print() functions.

I'm not a web (or any kind of) developer, so be gentle. This seems like the kind of thing AJAX is meant to handle with ease, so I was wondering if anyone has any advice before I go reinventing the wheel.

Thanks very much!

[Ron]

Well, how hard this would be would really depend on exactly what you want it to do. I am not sure if we have code that converts a table to XML.. Anyone?

[Agonostis]

My immediate goal is to click a "weather" button on a webpage, have it asynchronously query the Lua Global table to retrieve the weather.Local.cc table for parsing and display on the webpage.

More broadly, while the G examples have a robust solution for retrieving the data/type of a single variable, I'd like to be able to pass data back and forth in bigger chunks.

It doesn't necessarily have to be XML, check out this article (http://www.softwaresecretweapons.com/jspwiki/Wiki.jsp?page=AJAXWithoutXML) about forming the server response as JavaScript code.

Thanks for looking at/thinking about this Ron.

[Ron]

That would be cool. I don't have too much time right now. Maybe some other day, but don't hold your breath.

[Agonostis]

I kludged a solution to this to fit my specific weather needs. I think it would be pretty easy to adapt this to fit whatever somebody else needed to do.

i added the following code to the ajaxreq.lhtml file:

if ( t.Weather ) then
local tempString=""
for key,value in pairs(weather.Local.cc) do
tempString=tempString.."var "..key.."=".."'"..tostring(value).."'"..";"
end
for key,value in pairs(weather.Local.Location) do
tempString=tempString.."var "..key.."=".."'"..tostring(value).."'"..";"
end
for key,value in pairs(weather.Local.cc.TimeStamp) do
tempString=tempString.."var "..key.."=".."'"..tostring(value).."'"..";"
end
for i=1,7 do
for key,value in pairs(weather.Local.fc[i]) do
tempString=tempString.."var "..key..i.."=".."'"..tostring(value).."'"..";"
end
end
--print(tempString)
webserver:print(tempString)


end

and then use the javascript eval() function on the .responseText in the actual web page. Then all the weather info is available to use in conveniently named variables.

[Ron]

Hmm, I think there are some issues with threading here. I'll get Mike's opinion on this.

[Agonostis]

It seems to be working ok for the time being...perhaps not quite as fast as I might have liked, but hasn't crashed or anything.

[Ron]

If the weather object updates right in the middle of you pushing the info to the webbrowser you might get unexpected results. Not a crash probably but just bad data.

[Promixis]

These functions are for getting data.

Usage...

Weather.XXX:Get...

XXX = location

Use Local for default location



GetCWSmallIcon = function (self,iconnumber)
return win.GetDirectory('GIRDERDIR').."\\CWIcons\\Small\\"..(iconnumber or "")..".gif"
end,


GetCWLargeIcon = function (self,iconnumber)
return win.GetDirectory('GIRDERDIR').."\\CWIcons\\Large\\"..(iconnumber or "")..".gif"
end,


GetCWAnimSmallIcon = function (self,iconnumber)
return win.GetDirectory('GIRDERDIR').."\\CWIcons\\AnimatedSmall\\"..(iconnumber or "")..".gif"
end,

GetCWAnimLargeIcon = function (self,iconnumber)
return win.GetDirectory('GIRDERDIR').."\\CWIcons\\AnimatedSmall\\"..(iconnumber or "")..".gif"
end,

GetCurrentConditions = function (self) -- always returns a value so no need to check for nils..
local w = self:GetCC ()
if w and w.Observations and w.Observations [1]then
local xxx = w.Observations [1]
return {
BarometricPressure = xxx.baro_pressure or "?",
BarometricTendency = xxx.baro_tendency or "?",
DewPoint = xxx.dew_point or "?",
Humidity = xxx.humidity or "?",
Icon = xxx.icon or "",
IconName = xxx.icon_name or "?",
IconSmallFilename = self:GetCWSmallIcon (xxx.icon),
IconAnimSmallFilename = self:GetCWAnimSmallIcon (xxx.icon),
IconLargeFilename = self:GetCWLargeIcon (xxx.icon),
IconAnimLargeFilename = self:GetCWAnimLargeIcon (xxx.icon),
Precipitation = xxx.precip or "?",
PrecipitationDescription = xxx.precip_desc or "?",
Temperature = xxx.temperature or "?",
TemperatureDescription = xxx.temp or "?",
Visibility = xxx.visibility or "?",
WindDirectionDegrees = xxx.wind_dir or "?",
WindDirectionLong = xxx.wind_long or "?",
WindDirectionShort = xxx.wind_short or "?",
WindSpeed = xxx.wind_speed or "?",
SkyDescription = xxx.sky or "?",
Description = xxx.desc or "?",
TimeStamp = w.TimeStamp or "?",
Location = self.Location or "?",
Metric = self.Metric,
}
else
return nil
end
end,


GetForecastConditions = function (self)
local w = self:GetFC ()
if w and w.Forecast and w.Forecast [1] then
local Days = {}
for i in ipairs (w.Forecast) do
local xxx = w.Forecast [i]
Days [i] = {
Date = xxx.date or "?",
DayofWeek = xxx.day_of_week or "?",
DayofForecast = xxx.day_sequence or "?",
WeekDay = xxx.weekday or "?",
Description = xxx.description or "?",
DewPoint = dewpoint or "?",
Humidity = xxx.humidity or "?",
Icon = xxx.icon or "",
IconNam = xxx.icon_name or "?",
IconSmallFilename = self:GetCWSmallIcon (xxx.icon),
IconAnimSmallFilename = self:GetCWAnimSmallIcon (xxx.icon),
IconLargeFilename = self:GetCWLargeIcon (xxx.icon),
IconAnimLargeFilename = self:GetCWAnimLargeIcon (xxx.icon),
Beaufort = xxx.beaufort or "?",
BeaufortDescription = xxx.beaufort_desc or "?",
HighTemp = xxx.high_temp or "?",
LowTemp = xxx.low_temp or "?",
Precip = xxx.precip or "?",
PrecipDescription = xxx.precip_desc or "?",
PrecipProbability = xxx.precip_prob or "?",
Rainfall = xxx.rainfall or "?",
Sky = xxx.sky or "?",
SkyDescription = sky_desc or "?",
Snowfall = xxx.snowfall or "?",
Temp= xxx.temp or "?",
TempDescription = xxx.temp_desc or "?",
UV =xxx.uv or "?",
WindDirectionDegrees = xxx.wind_dir or "?",
WindDirectionLong = xxx.wind_long or "?",
WindDirectionShort = xxx.wind_short or "?",
WindSpeed = xxx.wind_speed or "?",
}
end
Days.TimeStamp = w.TimeStamp or "?"
Days.Location = self.Location or "?"
Days.Metric = self.Metric
return Days
else
return nil
end
end,


GetDetailedForecastConditions = function (self)
local w = self:GetDFC ()
if w and w.Forecast and w.Forecast [1] then
local Days = {}
for i in ipairs (w.Forecast) do
local xxx = w.Forecast [i]
Days [i] = {
Air = xxx.air or "?",
Comfort = xxx.comfort or "?",
DayofWeek = xxx.day_of_week or "?",
DaySegment = xxx.day_seqment or "?",
WeekDay = xxx.weekday or "?",
Description = xxx.description or "?",
DewPoint = dewpoint or "?",
Humidity = xxx.humidity or "?",
Icon = xxx.icon or "",
IconNam = xxx.icon_name or "?",
IconSmallFilename = self:GetCWSmallIcon (xxx.icon),
IconAnimSmallFilename = self:GetCWAnimSmallIcon (xxx.icon),
IconLargeFilename = self:GetCWLargeIcon (xxx.icon),
IconAnimLargeFilename = self:GetCWAnimLargeIcon (xxx.icon),
Beaufort = xxx.beaufort or "?",
BeaufortDescription = xxx.beaufort_desc or "?",
HighTemp = xxx.high_temp or "?",
LowTemp = xxx.low_temp or "?",
Precip = xxx.precip or "?",
PrecipDescription = xxx.precip_desc or "?",
PrecipProbability = xxx.precip_prob or "?",
Rainfall = xxx.rainfall or "?",
Sky = xxx.sky or "?",
SkyDescription = sky_desc or "?",
Snowfall = xxx.snowfall or "?",
Temp= xxx.temp or "?",
Temperature = xxx.temperature or "?",
TempDescription = xxx.temp_desc or "?",
UV =xxx.uv or "?",
WindDirectionDegrees = xxx.wind_dir or "?",
WindDirectionLong = xxx.wind_long or "?",
WindDirectionShort = xxx.wind_short or "?",
WindSpeed = xxx.wind_speed or "?",
Visibility = xxx.visibility or "?",
}
end
Days.TimeStamp = w.TimeStamp or "?"
Days.Location = self.Location or "?"
Days.Metric = self.Metric
return Days
else
return nil
end
end,


GetSatelliteMapFilename = function (self)
return self:GetSatMapFilename ()
end,

GetAnimatedSatelliteMapFilename = function (self)
return self:GetSatMapAnimFilename ()
end,

[harleydude]

I am attempting to use the above methods of retreiving the weather data, but am not sure of the actual calls to make. Can some one provide me with a working code sample for GetCurrentConditions?

Thanks