php - google map info window multiple addresses via xml

Question

I'm using the Google map code below to retrieve and plot markers for multiple addresses from an XML file dynamically created with PHP. The code is doing everything I need except for displaying the correct information in the Google map info window for the corresponding marker. I get the information of the last XML item/listing for all the markers.

I've been searching and trying different variations to get it to work, but no luck.

sample XML data

<?xml version="1.0" encoding="UTF-8"?>
<listings>
<listing>
    <address>123 Street</address>
    <city>MANOTICK</city>
</listing>
<listing>
    <address>456 Street</address>
    <city>MANOTICK</city>
</listing>
<listing>
    <address>111 Avenue</address>
    <city>MANOTICK</city>
</listing>
<listing>
    <address>777 Avenue</address>
    <city>Ottawa</city>
</listing>
<listing>
    <address>333 Street</address>
    <city>Manotick</city>
</listing>
</listings>

google map code

function initialize ()
{
    var myLatLng = new google.maps.LatLng(45.2340684, -75.6287287);
    var myOptions =
    {
        zoom: 10,
        mapTypeControl: true,
        center: myLatLng,
        zoomControl: true,
        zoomControlOptions:
        {
            style: google.maps.ZoomControlStyle.SMALL
        },
        StreetViewControl: false,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    }
    var map = new google.maps.Map(document.getElementById('google_map'), myOptions);
    var info_window = new google.maps.InfoWindow;
    google.maps.event.addListener
    (map, 'click',
    function ()
    {
        info_window.close();
    });


    downloadUrl
    ('listings.xml',
    function (listings_data)
    {
        var markers = listings_data.documentElement.getElementsByTagName('listing');
        var geocoder = new google.maps.Geocoder();
        for (var i = 0; i < markers.length; i++)
        {
            var address = markers[i].getElementsByTagName('address')[0].firstChild.data;
            var city = markers[i].getElementsByTagName('city')[0].firstChild.data;
            var address_google_map = address + ', ' + city + ', ON';
            var info_text = address + '<br />' + city + ' ON';

            geocoder.geocode
            ({'address': address_google_map},
            function (results)
            {
                    var marker = new google.maps.Marker
                    ({
                        map: map, 
                        position: results[0].geometry.location
                    });
                    google.maps.event.addListener
                    (marker, 'click',
                    function()
                    {
                        info_window.setContent(info_text);
                        info_window.open(map, marker);
                    });
            });
        }
    });
}

Answer 1

You have a problem with the asynchronous nature of the geocoder, and if you add many addresses you will have a problem with the geocoder quota/rate limits (particularly since your code doesn't look at the return status of the geocoder).

All these questions are related:

• Google Maps Api v3: Info window displaying same information for all the markers on the map
• GMaps API V3 - Multiple Markers & InfoWindow
• Google Map multiple infowindow does not work

The simplest solution is to use function closure to associate the call to the geocoder with the returned result:

geocodeAddress(xmldata)
{
        var address = xmldata.getElementsByTagName('address')[0].firstChild.data;
        var city = xmldata.getElementsByTagName('city')[0].firstChild.data;
        var address_google_map = address + ', ' + city + ', ON';
        var info_text = address + '<br />' + city + ' ON';

        geocoder.geocode
        ({'address': address_google_map},
        function (results, status)
        {
          if (status == google.maps.GeocoderStatus.OK) {
            createMarker(results[0].geometry.location, info_text);
          } else { 
            alert("geocode of "+ address +" failed:"+status);
          }
        });
    }

And a createMarker function to associate the infowindow content with the marker:

function createMarker(latlng, html)
{
  var marker = new google.maps.Marker
                ({
                    map: map, 
                    position: latlng
                });
  google.maps.event.addListener(marker, 'click', function() {
                    info_window.setContent(html);
                    info_window.open(map, marker);
                });
}

Makes your for loop:

for (var i = 0; i < markers.length; i++)
{
  geocodeAddress(markers[i]);
}

Working example