[edlug] Google Maps API Problem

[Max Manders <max@xxx.xxx.xxx>]

Hi,

I'm working on a wee project that will use Google Maps, my apologies if 
my examples seem contrived or obfuscated.  I'm having some problems with 
some geocoding and was hoping that someone on list might be have some 
thoughts...

So, user enters postcode.  I do an AJAX request to a homegrown API that 
returns a list of addresses as XML, including postcodes _associated_ 
with the user-entered postcode.

Due to inaccuracies in the Google GClientGeocoder object (grrr Royal 
Mail), I have instead used the GLocalSearch object, and parsed out the 
first result (which is a more accurate Lng/Lat point).

// AJAX call, iterate over resulting postcodes, and call
// usePointFromPostcode with a callback to add a marker.
[code]
...
var url="/api/eh52gj";
new Ajax.Request(url, {
  method: 'get',
  onSuccess: function(transport) {
    var addrs = transport.responseXML.getElementsByTagName('addrs');
    for (var i = 0; i < stores.length; i++) {
      var postcode =
      addrs[i].getElementsByTagName('postcode')[0]...
        .childNodes[0].nodeValue;
      usePointFromPostcode(postcode, placeMarkerAtPoint);
    }
  }
});
...
[/code]

// This function _geocodes_ a postcode using LocalSearch, and if as
// above, the placeMarkerAtPoint callback is given, a marker ovarlay
// is placed on the map.
[code]
function usePointFromPostcode(postcode, callbackFunction) {
  localSearch = new google.search.LocalSearch();
  localSearch.setSearchCompleteCallback(null, function() {
    if (localSearch.results[0]) {
      var resultLat = localSearch.results[0].lat;
      var resultLng = localSearch.results[0].lng;
      var point = new GLatLng(resultLat,resultLng);
      callbackFunction(point);
      map.panTo(point);
    }
  });

  localSearch.execute(postcode + ", UK");
}
[/code]

I believe that the call to localSearch.execute is performed 
asynchronously, and that the callback closure is only called when the 
search has completed.  I further believe that this is causing only the 
first and last postcode in the initial loop to be successfully geocoded.

Does anyone know how to serialise such calls, or detect when the search 
is completed such that I only call usePointFromPostcode in loop k+1 if 
the call in loop k has completed?

Many Thanks,
Max
--
Max Manders
max@xxx.xxx.xxx
http://maxmanders.co.uk
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