google maps clustering in asp.net page

Question

I have asp.net web forms page which has repeater to show multiple markers at the page. I want to cluster the markers, I followed some examples found online but no success so far. This is what I have:

1. html markup:

   
   

   var markers = [
        <asp:Repeater ID="rptMarkers" runat="server">
        <ItemTemplate>
                 {
                     "title": '<%# Eval("Name") %>',
                     "lat": '<%# Eval("Latitude") %>',
                     "lng": '<%# Eval("Longitude") %>',
                     "description": '<%# Eval("Name") %>'
                 }
    </ItemTemplate>
    <SeparatorTemplate>
        ,
    </SeparatorTemplate>
    </asp:Repeater>
        ];

        var mapOptions = {
            center: new google.maps.LatLng(43.648399, -79.485703),
            zoom: 8,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        var map  = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
        var markerCluster = new MarkerClusterer(map, markers, mapOptions );
    </script>
    <script type="text/javascript">

        window.onload = function () {
            var mapOptions = {
                center: new google.maps.LatLng(43.648399, -79.485703),
                zoom: 8,
                mapTypeId: google.maps.MapTypeId.ROADMAP
            };
            var infoWindow = new google.maps.InfoWindow();
            var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
            for (i = 0; i < markers.length; i++) {
                var data = markers[i]
                var myLatlng = new google.maps.LatLng(data.lat, data.lng);
                var marker = new google.maps.Marker({
                    position: myLatlng,
                    map: map,
                    title: data.title
                });
                (function (marker, data) {
                    google.maps.event.addListener(marker, "click", function (e) {
                        infoWindow.setContent(data.description);
                        infoWindow.open(map, marker);
                    });
                })(marker, data);
            }
        }
    </script>
    <div id="dvMap" style="width: 500px; height: 277px">
    </div>


            </div>

Then, in the backend file I am getting all the data from database and sending to the repeater which properly renders multiple markers, as you can see at this screenshot as well: http://gyazo.com/049821984b889eefa551df663af0d2eb.png

This is the section I was trying to use to get the clustering working (visible in the code above as well):

  var mapOptions = {
            center: new google.maps.LatLng(43.648399, -79.485703),
            zoom: 8,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        var map  = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
        var markerCluster = new MarkerClusterer(map, markers, mapOptions );

When I view the source of the page this is the content I am getting regarding the markers data:

<div class="divdisplay">  
          <script type="text/javascript" src="http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markerclusterer/src/markerclusterer.js"></script>
                <script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
<script type="text/javascript">
    var markers = [

             {
                 "title": 'Product Specialist',
                 "lat": '43.6877731',
                 "lng": '-79.2709108',
                 "description": 'Product Specialist'
             }

    ,

             {
                 "title": 'Finance Manager',
                 "lat": '43.7345524',
                 "lng": '-79.2561590',
                 "description": 'Finance Manager'
             }

    ,

             {
                 "title": 'New Job',
                 "lat": '43.7598255',
                 "lng": '-79.2252689',
                 "description": 'New Job'
             }

    ,

             {
                 "title": 'AD, Algorithmic Trading Development Team ',
                 "lat": '43.7240344',
                 "lng": '-79.3006776',
                 "description": 'AD, Algorithmic Trading Development Team '
             }

    ,

             {
                 "title": 'Financial Analyst - Investment Finance Systems Ana',
                 "lat": '43.7870613',
                 "lng": '-79.2761657',
                 "description": 'Financial Analyst - Investment Finance Systems Ana'
             }

    ,

             {
                 "title": 'New Business Coordinator CSR - Group Benefits',
                 "lat": '43.7891500',
                 "lng": '-79.1404511',
                 "description": 'New Business Coordinator CSR - Group Benefits'
             }

    ,

             {
                 "title": 'TD Job 1',
                 "lat": '43.7092267',
                 "lng": '-79.2962398',
                 "description": 'TD Job 1'
             }

    ,

             {
                 "title": 'Web Designer',
                 "lat": '43.7841207',
                 "lng": '-79.2917106',
                 "description": 'Web Designer'
             }

    ,

             {
                 "title": 'ceo',
                 "lat": '43.6488293',
                 "lng": '-79.3965691',
                 "description": 'ceo'
             }

    ,

             {
                 "title": 'IT Analyst',
                 "lat": '43.6546566',
                 "lng": '-79.3805941',
                 "description": 'IT Analyst'
             }

    ,

             {
                 "title": 'Part-Time MARKET RESEARCH INTERVIEWERS',
                 "lat": '43.6683729',
                 "lng": '-79.4392835',
                 "description": 'Part-Time MARKET RESEARCH INTERVIEWERS'
             }

    ];    

    var mapOptions = {
        center: new google.maps.LatLng(43.648399, -79.485703),
        zoom: 8,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    var map  = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
    var mcOptions = {gridSize: 50, maxZoom: 15};
    var markerCluster = new MarkerClusterer(map, markers, mcOptions);
</script>
<script type="text/javascript">

    window.onload = function () {
        var mapOptions = {
            center: new google.maps.LatLng(43.648399, -79.485703),
            zoom: 8,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        var infoWindow = new google.maps.InfoWindow();
        var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
        for (i = 0; i < markers.length; i++) {
            var data = markers[i]
            var myLatlng = new google.maps.LatLng(data.lat, data.lng);
            var marker = new google.maps.Marker({
                position: myLatlng,
                map: map,
                title: data.title
            });
            (function (marker, data) {
                google.maps.event.addListener(marker, "click", function (e) {
                    infoWindow.setContent(data.description);
                    infoWindow.open(map, marker);
                });
            })(marker, data);
        }
    }
</script>
<div id="dvMap" style="width: 500px; height: 277px">
</div>


        </div>

Every advice is greatly welcome. Thanks, Laziale

Answer 1

You need to pass an array of google.maps.Marker objects to the marker clusterer - you're passing your array of initial marker data.

You need to create a new MarkerClusterer after all markers have been created, not before. So, remove these lines from the first script block in your example:

var mcOptions = {gridSize: 50, maxZoom: 15};
var markerCluster = new MarkerClusterer(map, markers, mcOptions);

We'll move these to after all the markers have been created. So change your window.onload function to this:

<script type="text/javascript">
window.onload = function () {
    var mapOptions = {
        center: new google.maps.LatLng(43.648399, -79.485703),
        zoom: 8,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };


    // declare an array to keep all google.maps.Marker instances in:
    var googleMarkers = []; 


    var infoWindow = new google.maps.InfoWindow();
    var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
    for (i = 0; i < markers.length; i++) {
        var data = markers[i]
        var myLatlng = new google.maps.LatLng(data.lat, data.lng);
        var marker = new google.maps.Marker({
            position: myLatlng,
            map: map,
            title: data.title
        });



        // add the new marker to the googleMarkers array
        googleMarkers.push(marker);



        (function (marker, data) {
            google.maps.event.addListener(marker, "click", function (e) {
                infoWindow.setContent(data.description);
                infoWindow.open(map, marker);
            });
        })(marker, data);
    }


    // now all the markers have been created, make a new MarkerClusterer:
    var mcOptions = {gridSize: 50, maxZoom: 15};
    var markerCluster = new MarkerClusterer(map, googleMarkers, mcOptions);

}
</script>