Getting user's location using Google from .NET code

Question

I want to store a user's current location on an ASP.NET MVC website for the duration of a session. Because I want to use the location server-side, the way I think this should work (maybe other suggestions?) is that when a user first hits the website, I get the location and store it in the session, so on later requests it does not have to be looked up again.

The best way I can find is to use Google's ClientLocation method:

<script src="http://www.google.com/jsapi?key=YOURAPIKEY" type="text/javascript"></script>
<script>
    google.load("jquery", "1.2.6");
    google.load("jqueryui", "1.5.2");
    var yourLocation = google.loader.ClientLocation.address.city + ", "
       + google.loader.ClientLocation.address.region;
</script>

My question is how best to get the location looked up in this Javascript code back to the server to store in the database or in the session. I know that I could call a controller action using jQuery to pass the location:

$.post("/Home/StoreLocation", location, function(){});

But for performance I don't want this to be happening on every single page load. The other way i thought to do it was to call Google's apis from .NET code by doing something like this (a call to geocoding):

string path = "http://maps.google.com/maps/geo?q=" + strAddress + "&output=csv&key=" + apiKey;
WebClient client = new WebClient();
string[] eResult = client.DownloadString(sPath).ToString().Split(',');
//Parse the array

But I can't find any equivalent way to call ClientLocation directly from a URL like this - all the examples I have seen use google.loader (which I don't think I can use when doing it this way?) Another thing I have considered is using Google's .NET library, but I can't find anything in there to do a location lookup (maybe I am wrong?).

Any suggestions greatly appreciated - I feel I am over-thinking this and missing something obvious!

Answer 1

In your second example, I don't quite understand strAddress. Do you have the client's address? Or is that their IP? I just tried that URL with my IP address and it says I'm about 1000 miles away.

Anyways, I don't see what's wrong with #1. Just have something like this in your Site.Master:

<script type="text/javascript">
  //other javascript here
  <% if (Sesssion.Contents["has_location"] == null) { %>
    $(document).ready(function_to_submit_location)
  <% } %>
</script>

edited to put the if statement in ASP tags -- it's not a javascript if.

edit for those that want to use this code you'd have to put something in your controller in order to set session["has_location"] = true when you get the location.

Answer 2

This question prompted me to finish off a blog post I had in my draft folder: http://www.alexjamesbrown.com/geek/development/dotnet/reverse-geocoding-with-google-api-and-c/

Please let me know if that's of any help (it's not quite what you are asking... but it could be adapted to do what you want)

Answer 3

The Google Client Location Method is designed to be used on the front end/in the browser. It sounds like you're looking for something that would run on your server - either a web service or a local IP database.

MaxMind's has a free GeoIP database with a C# api. You pass the client's IP address to the GeoIP library and it returns the city and state.

http://www.maxmind.com/app/geolitecity

MaxMind also has a webservice available for a nominal fee.