Parsing JSON error (from PhoneGap to Ruby)

Question

I'm attempting to send a JSON string from PhoneGap to my Ruby application. In PhoneGap, the following code is sending the JSON string:

            var location = {
                lat: position.coords.latitude,
                lng: position.coords.longitude
            }

            $.ajax({
              type: "post",
              dataType: 'json',
              data: location,
              url: 'http://localhost:3000/location/new'
            });

In my Ruby app, I have a controller trying to process the response:

def addlocation

    require 'json'
    json_string = params[:data]

    parsed_json = JSON.parse(json_string.to_json)

    if parsed_json["app"] == "Inrix PhoneGap"
        new_obj = Location.new
        new_obj.lat = parsed_json["lat"].to_f
        new_obj.lng = parsed_json["lng"].to_f
        new_obj.save
    end

end

I know I'm getting the data from PhoneGap, because the parameters show up in the server log. I tried converting the response to a string, and then to json, because it doesn't appear to be in the proper json format. I've also tried passing the JSON.parse function response.body and params[:data]. Here is the error I receive in the server log:

Started POST "/location/new" for 127.0.0.1 at 2013-07-23 01:14:37 -0700
Processing by LocationsController#addlocation as HTML
  Parameters: {"lat"=>"37.785834", "lng"=>"-122.406417"}
Completed 500 Internal Server Error in 0ms

JSON::ParserError (757: unexpected token at 'null'):
  app/controllers/locations_controller.rb:12:in `addlocation'


  Rendered /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.1ms)
  Rendered /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.9ms)
  Rendered /usr/local/rvm/gems/ruby-1.9.3-p392/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (7.5ms)

Thanks in advance. Let me know if you need more information. Cheers!

Answer 1

data in $.ajax is not the name of the POST parameter. You need to give data: { data: location } in order to have a parameter named data (which would translate to POST data={"lat"=>"37.785834", "lng"=>"-122.406417"} )

However, I would suggest you name it something like location instead :P

$.ajax({
  type: "post",
  dataType: 'json',
  data: { location: location },
  url: 'http://localhost:3000/location/new'
});

and

location_json = params[:location]

just so you understand what you wrote six months from now :D