Google Maps API in wordpress

Question

I get "documentElement of null" error. I am trying to follow https://developers.google.com/maps/articles/phpsqlajax_v3 UPDATE: On using dev tools it seems that the "downloadUrl()" function has problems.

My "phpsqlajax_genxml.php" create_element("markers"); $parnode = $doc->append_child($node);

// Opens a connection to a mySQL server
/*$connection=mysql_connect (localhost, $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
}

// Set the active mySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
}*/

// Select all the rows in the markers table
global $wpdb ;
//$query = "SELECT * FROM markers WHERE 1";
$query = $wpdb->get_results("SELECT * FROM `markers` WHERE 1;") ;
/*no need of this
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
}*/

header("Content-type: text/xml");

// Iterate through the rows, adding XML nodes for each
 foreach ($query as $q) 
  {
  // ADD TO XML DOCUMENT NODE
  echo '<marker ';
  echo 'name="' . parseToXML($q->name) . '" ';
  echo 'address="' . parseToXML($q->address) . '" ';
  echo 'lat="' . $q->lat . '" ';
  echo 'lng="' . $q->lng . '" ';
  echo 'type="' . $q->type . '" ';
  echo '/>';
}
    ?>

My "hourly.php" file which takes xml from above file

 <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY"
        type="text/javascript"></script>
<script type="text/javascript">
//<![CDATA[

var customIcons = {
  restaurant: {
    icon: 'http://labs.google.com/ridefinder/images/mm_20_blue.png'
  },
  bar: {
    icon: 'http://labs.google.com/ridefinder/images/mm_20_red.png'
  }
};

function load() {
  var map = new google.maps.Map(document.getElementById("map"), {
    center: new google.maps.LatLng(47.6145, -122.3418),
    zoom: 13,
    mapTypeId: 'roadmap'
  });
  var infoWindow = new google.maps.InfoWindow;

  // Change this depending on the name of your PHP file
  downloadUrl("phpsqlajax_genxml.php", function(data) {
    var xml = data.responseXML;
    var markers = xml.documentElement.getElementsByTagName("marker");
    for (var i = 0; i < markers.length; i++) {
      var name = markers[i].getAttribute("name");
      var address = markers[i].getAttribute("address");
      var type = markers[i].getAttribute("type");
      var point = new google.maps.LatLng(
          parseFloat(markers[i].getAttribute("lat")),
          parseFloat(markers[i].getAttribute("lng")));
      var html = "<b>" + name + "</b> <br/>" + address;
      var icon = customIcons[type] || {};
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        icon: icon.icon
      });
      bindInfoWindow(marker, map, infoWindow, html);
    }
  });
}

function bindInfoWindow(marker, map, infoWindow, html) {
  google.maps.event.addListener(marker, 'click', function() {
    infoWindow.setContent(html);
    infoWindow.open(map, marker);
  });
}

function downloadUrl(url, callback) {
  var request = window.ActiveXObject ?
      new ActiveXObject('Microsoft.XMLHTTP') :
      new XMLHttpRequest;

  request.onreadystatechange = function() {
    if (request.readyState == 4) {
      request.onreadystatechange = doNothing;
      callback(request, request.status);
    }
  };

  request.open('GET', url, true);
  request.send(null);
}

function doNothing() {}

//]]>

Answer 1

Figured it out!!!!! Since we get the SQL query result with the help of "$wpdb" object we can access each row's attribute as an associative array. As a result there isn't a need for "mysql_fetch_assoc()" and "mysql_query()" functions. Also we need to define "$wpdb" object, so we require "wp-config.php" file.