cron job - geocode address field to lat & long in mySQL database - mysql

Question

Has anyone done this, or have an idea?
I have a real estate script that for whatever reasons (google mapping limits, script itself) only gets the coordinates for half of the listings. I want to run a script that of the lat & long field are empty the script will use the address, city, state to populate the lat & long fields.
THoughts?
Edit:
Here's a code from google, that does allow you to geocode for a database:
http://code.google.com/apis/maps/articles/phpsqlgeocode.html
<?php
require("phpsqlgeocode_dbinfo.php");
define("MAPS_HOST", "maps.google.com");
define("KEY", "abcdefg");
// 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
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
die("Invalid query: " . mysql_error());
}
// Initialize delay in geocode speed
$delay = 0;
$base_url = "http://" . MAPS_HOST . "/maps/geo?output=xml" . "&key=" . KEY;
// Iterate through the rows, geocoding each address
while ($row = #mysql_fetch_assoc($result)) {
$geocode_pending = true;
while ($geocode_pending) {
$address = $row["address"];
$id = $row["id"];
$request_url = $base_url . "&q=" . urlencode($address);
$xml = simplexml_load_file($request_url) or die("url not loading");
$status = $xml->Response->Status->code;
if (strcmp($status, "200") == 0) {
// Successful geocode
$geocode_pending = false;
$coordinates = $xml->Response->Placemark->Point->coordinates;
$coordinatesSplit = split(",", $coordinates);
// Format: Longitude, Latitude, Altitude
$lat = $coordinatesSplit[1];
$lng = $coordinatesSplit[0];
$query = sprintf("UPDATE markers " .
" SET lat = '%s', lng = '%s' " .
" WHERE id = '%s' LIMIT 1;",
mysql_real_escape_string($lat),
mysql_real_escape_string($lng),
mysql_real_escape_string($id));
$update_result = mysql_query($query);
if (!$update_result) {
die("Invalid query: " . mysql_error());
}
} else if (strcmp($status, "620") == 0) {
// sent geocodes too fast
$delay += 100000;
} else {
// failure to geocode
$geocode_pending = false;
echo "Address " . $address . " failed to geocoded. ";
echo "Received status " . $status . "
\n";
}
usleep($delay);
}
}
?>
I'm not sure where to start getting this to work with my database and my lat & long rows (declat and declong)
Any help would be appreciated. Thanks!

Answer 1

The best approach is obviously parsing the response and looking for the error code returned.
The most usual reason for this happening is
The requests going out too fast (add some throttling to your script)
Unicode characters like ÄÖÜ Umlauts being encoded wrongly
By the way, what you doing may be a violation of Google's Terms of Service:
Note: the Geocoding API may only be used in conjunction with a Google map; geocoding results without displaying them on a map is prohibited. For complete details on allowed usage, consult the Maps API Terms of Service License Restrictions.

Answer 2

I had the same requirement and got it working eventually:
This geocodes the addresses:
<?php
require("database.php");
function parseToXML($htmlStr)
{
$xmlStr=str_replace('<','<',$htmlStr);
$xmlStr=str_replace('>','>',$xmlStr);
$xmlStr=str_replace('"','"',$xmlStr);
$xmlStr=str_replace("'",''',$xmlStr);
$xmlStr=str_replace("&",'&',$xmlStr);
return $xmlStr;
}
// 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
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
die('Invalid query: ' . mysql_error());
}
header("Content-type: text/xml");
// Start XML file, echo parent node
echo '<markers>';
// Iterate through the rows, printing XML nodes for each
while ($row = #mysql_fetch_assoc($result)){
// ADD TO XML DOCUMENT NODE
echo '<marker ';
echo 'name="' . parseToXML($row['name']) . '" ';
echo 'address="' . parseToXML($row['address']) . '" ';
echo 'lat="' . $row['lat'] . '" ';
echo 'lng="' . $row['lng'] . '" ';
echo 'type="' . $row['type'] . '" ';
echo '/>';
}
// End XML file
echo '</markers>';
?>
And this generates the map (which I also cluster but you should be able to take that out):
<script type="text/javascript">
//<![CDATA[
var customIcons = {
restaurant: {
icon: 'http://labs.google.com/ridefinder/images/mm_20_blue.png',
shadow: 'http://labs.google.com/ridefinder/images/mm_20_shadow.png'
},
bar: {
icon: 'http://labs.google.com/ridefinder/images/mm_20_red.png',
shadow: 'http://labs.google.com/ridefinder/images/mm_20_shadow.png'
}
};
function load() {
var cluster = [];
var map = new google.maps.Map(document.getElementById("map"), {
center: new google.maps.LatLng(53.4788, -3.9551),
zoom: 6,
mapTypeId: 'roadmap'
});
var infowindow = new google.maps.InfoWindow();
// Change this depending on the name of your PHP file
downloadUrl("<?php bloginfo('stylesheet_directory'); ?>/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,
shadow: icon.shadow
});
google.maps.event.addListener(marker, 'click', (function(marker, i) {
return function() {
infowindow.setContent(markers[i].getAttribute("name"));
infowindow.open(map, marker);
}
})(marker, i));
cluster.push(marker);
}
var mc = new MarkerClusterer(map,cluster);
});
}
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() {}
//]]>
</script>

Answer 3

You are allowed 2500 geocodes per day. That's is a fair amount, but you can't just bombard the service with your requests. You need to provide a delay between each request, or else it will start blocking service.
Once you geocode, you should store the value within the database and mark it as geocoded, so you don't have to request it again. Then you can just geocode the rest as time goes on.