Google Maps API Marker Clusterer and Ajax

Question

I am running multiple ajax calls to download a large number of google maps icons. When I try to increment the Marker Clusterer, however, the map clears all markers. I believe this is because I am calling var markerCluster = new MarkerCluster(map); in each AJAX call.

Can anyone tell me how to correctly implement this?

var populateMapByIncident = function(incident, page) {
  var run_again = false;
  $.getJSON(
    "/public_map_ajax_handler",
    {"shortname" : incident, "page": page},
    function(sites_list) {
    if (sites_list.length > 2) {
      run_again = true;
    }
          var mapOptions = {
    zoom: 8,
    center: new google.maps.LatLng(40.6501038, -73.8495823),
    mapTypeId: google.maps.MapTypeId.ROADMAP
    }
    var map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
       var markers = [];
       var i = 0;


   for (var i = 0; i < sites_list.length; i++) {
 var latLng = new google.maps.LatLng(sites_list[i].latitude, sites_list[i].longitude);
 var marker = new google.maps.Marker({'position': latLng, 
                     'icon': getMarkerIcon(sites_list[i]), 
                     'site_id': sites_list[i].id, 
                      'case_number': sites_list[i].case_number, 
                      'work_type': sites_list[i].work_type, 
                      'floors_affected': sites_list[i].floors_affected, 
                      'status': sites_list[i].status});
 markers.push(marker);
 var site_id = sites_list[i].id;
google.maps.event.addListener(marker, "click", function() {
  new Messi('<p>Name, Address, Phone Number are removed from the public map</p><p>Details: work type: '
  + this.work_type+ ', floors affected: ' + this.floors_affected + '</p>' + '<p>Status: ' + this.status + '</p>',
  {title: 'Case Number: ' + this.case_number, titleClass: 'info', 
  buttons: [
  {id: 0, label: 'Printer Friendly', val: "On the live version, this would send all of this site's data to a printer friendly page." }, 
  {id: 1, label: 'Change Status', val: "On the live version, you would be able to change the site's status here."}, 
  {id: 2, label: 'Edit', val: "On the live version, you would be able to edit the site's info, as new details come in."}, 
  {id: 3, label: 'Claim', val: "On the live version, clicking this button would 'Claim' the site for your organization, letting other organizations know that you intend to work on that site"},
  {id: 4, label: 'Close', val: 'None'}], callback: function(val) { if (val != "None") {Messi.alert(val);} }});

});
   }

   var markerCluster = new MarkerClusterer(map);
   markerCluster.addMarkers(markers);


    if (run_again == true) {
  populateMapByIncident(incident, page + 1, markers);
} else {
      markerCluster.addMarkers(markers);
}

}

  );

}

Answer 1

I am running multiple ajax calls to download a large number of google maps icons. When I try to increment the Marker Clusterer, however, the map clears all markers. I believe this is because I am calling var markerCluster = new MarkerCluster(map); in each AJAX call.

Can anyone tell me how to correctly implement this?

Don't do that. Create the MarkerClusterer one time in the global scope (outside of any function), and add markers to it when you receive them from the server (assuming you aren't sending any duplicates).

See the documentation

Looks like you are already adding arrays of markers to the MarkerClusterer:

addMarkers(markers:Array., opt_nodraw:boolean) | None | Add an array of markers to the clusterer.

All you really need to do is move where you create the MarkerClusterer to the global scope. One suggestion below.

var markerCluster = new MarkerClusterer(map);  // <------------- add this
var populateMapByIncident = function(incident, page) {
  var run_again = false;
  $.getJSON(
// ----- existing code ------- //
// leave as is
// ----- modification -------- //
// var markerCluster = new MarkerClusterer(map); <----------- remove this
   markerCluster.addMarkers(markers);

   if (run_again == true) {
    populateMapByIncident(incident, page + 1, markers);
   } else {
    markerCluster.addMarkers(markers);
   }