Saturday, 1 March 2008

Google Maps Placemark

This post has been sitting for quite a while now, pending me having time to sit down and write some text to go alongside the code. It would appear that I now have the time to write it up.

Back when I was writing my Google Maps property finder I was using Google's Geocoding API to get a set of co-ordinates based on a search string.

Specifically I was using the getLocations method of the GClientGeocoder object. This would return a number of Placemark objects with a bunch of information about the potential matches. They don't really document this object, but to be honest they don't really need to, below is an example Placemark expressed in JSON-ish notation.

{   "id": "p1",
    "address": "1600 Amphitheatre Pkwy, Mountain View, CA 94043, USA",
    "AddressDetails": {
        "Country": {
            "CountryNameCode": "US",
            "AdministrativeArea": {
                "AdministrativeAreaName": "CA",
                "SubAdministrativeArea": {
                    "SubAdministrativeAreaName": "Santa Clara",
                    "Locality": {
                        "LocalityName": "Mountain View",
                        "Thoroughfare": {
                            "ThoroughfareName": "1600 Amphitheatre Pkwy"},
                            "PostalCode": {
                                "PostalCodeNumber": "94043"
                            }
                        }
                    }
                }
            },
        "Accuracy": 8
        },
    "Point": {
        "coordinates": [-122.081783,37.423111,0]
    }
}

The only thing is, if you want to get a specific element, the tree will not necessarily be the same each time, so traversal is a pain. The code below will condense all this into the root level of an object, so you can pick out the key/value pairs you want, and easily tell if some aren't there.

var Placemark = new Class({
 initialize: function(placemark){
  this.traverse(placemark);
 },
 traverse: function(item, key) {
  for (var key in item) {
   
   if (key == 'prototype')
    continue;
    
   if(typeof(item[key]) != 'object')
    this[key] = item[key];
   else
    this.traverse(item[key]);
  }
 }
})

One thing to note is that this was written for to use the Mootools class system, though it shouldn't be very hard to remove this dependancy.

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