Help with PHP/MYSQL

dkar · September 9, 2012

Hi,

I just started learning php and I face some problems with my code. I am trying to read coordinates from a table in a database and display them as markers on a google map. I did this but then I want to have a drop down menu and by selecting a specific value (eg activity = climbing) - the corresponding marker should appear.

I have two separate files of code. In the php code, in the sql query (in red) if I have in the WHERE clause: name='$category' the code returns nothing. If I put a specific value from the table (like name='restaurant') then it works fine. So, it seems that it can not get the value from the dropdown menu which is in the second file. It must be something very simple that I am missing here. Some logical mistake I guess. Any ideas?

Why I can not get the value of the dropdown menu?

<?php
require("connectmarker.php");

$category = $_POST['category'];

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
[color=red]$query = "SELECT * FROM markers WHERE name='$category'";[/color]
$result = mysql_query($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>';

?>

***************

!DOCTYPE html >
  <head>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
    <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
    <title>PHP/MySQL & Google Maps Example</title>
    <script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
    <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 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("markers.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
          });
          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() {}

    //]]>

  </script>

  </head>

  <body>
    <div id="map" style="width: 500px; height: 300px"></div>

<form>
[color=red] <label> choose activity:
		<select name="category">
        <option value="Pan Africa Market">Pan Africa Market</option>
        <option value="Golf">Golf</option>
        <option value="Hiking">Hiking</option>
    	</select>
</label>[/color]
</form>
    <input type="submit" onClick="load()">

  </body>

</html>

cyberRobot · September 10, 2012

It looks like your form goes straight to JavaScript. To use PHP code, the form data needs to be sent back to the server for processing.

dkar · September 10, 2012

Yes, I was thinking it must be related to this. If I add an action='file.php' on the form tag then I get as a result the xml file. Do you have any idea what I should do?

lemmin · September 10, 2012

Without an action attribute set in your form tag, the default value of GET will be used. You are using the $_POST variable in your PHP, though. Adding "action='POST'" or using the $_GET variable should populate your $category variable.

cyberRobot · September 11, 2012

One way is to merge both the PHP and JavaScript code. For example, here's a simplified code snippet from a Google Map I created earlier in the year.

<?php
$sql = "SELECT id, name, latLong FROM tableName ORDER BY name";
$result = mysql_query($sql);
while($row = mysql_fetch_array($result)) {
?>
//ADD MAP MARKER FOR CURRENT ENTRY
var marker<?php print $row['id']; ?> = new google.maps.Marker({
	position: new google.maps.LatLng(<?php print $row['latLong']; ?>),
	map: map,
	title:"<?php print $row['name']; ?>"
});
<?php
}
?>

If you prefer to add the markers with XML, the above code could be modified to meet those needs.

Instead of loading the map after the submit button is clicked, you would load it when the PHP part is done using something like this:

https://developers.google.com/maps/documentation/javascript/tutorial#asynch

dkar · September 12, 2012

Ok! Thanks. I will try to make it work by merging java and php together!

Thanks a lot.

D.

cyberRobot · September 12, 2012

Ok! Thanks. I will try to make it work by merging java and php together!

Thanks a lot.

D.

For what it's worth, it's actually JavaScript. Java is a totally different programming language. I know picky, picky.

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