Geo-Targetting

[listenmirndt]

Hi, I am attempting to follow this tutorial :

http://www.phpro.org/tutorials/Geo-Targetting-With-PHP-And-MySQL.html#1

Using the code :

<?php

/*
 *
 * @get spacial proximity based on zip/post code
 *
 * @param int $zip
 *
 * @param int $distance
 *
 * @param int $precision
 *
 * @param int $unit, default 'K'
 *
 * @return array
 *
 */
function getSpatialProximityByZip($zip, $distance, $precision, $unit='K')
{
    /*** the sql ***/
    $sql = "CALL zip_radius(:unit, :zip, :distance, :precision)";

try
{
    /*** an instance of PDO singleton ***/
    $stmt = db::getInstance()->prepare($sql);
    /*** bind the paramaters ***/
    $stmt->bindParam(':zip', $zip, PDO::PARAM_INT);
    $stmt->bindParam(':unit', $unit, PDO::PARAM_STR);
    $stmt->bindParam('distance', $distance, PDO::PARAM_INT);
    $stmt->bindParam(':precision', $precision, PDO::PARAM_INT);

    /*** execute the query ***/
    $stmt->execute();
    /*** return the distance ***/
    return $stmt->fetchAll(PDO::FETCH_ASSOC); 
}
catch( Exception $e )
{
echo $e->getMessage();
return false;
}
}
?>




<?php

/*** call funciton with zip code ***/
$cities = getSpatialProximityByZip(28034, 10, 2, 'M');

/*** loop over the result set ***/
foreach( $cities as $city )
{
    /*** print the arrays ***/
        print_r($city);
}

?>

I am getting an error :
Fatal error: Class 'db' not found

I can't see anything that I missed.. if anyone has some insight, would be most appreciated!

[johanafm]

$stmt = db::getInstance()->prepare($sql);

This statement calls getInstance() which is a static method of the class 'db'. For this to work, you need
1. The class 'db'
2. It must be included.
Either: require_once 'path/to/db.php';
Or: use autoload

[listenmirndt]

thanks for the reply, where is the db.php file located?

i also tried to make sense of the autoload function

<?php
function __autoload($class_name) {
    require_once $class_name . '.php';
}

$obj  = new db();
?>

which turns a : failed to open stream: No such file error.

sure i am missing something simple here, thanks for the help!

[johanafm]

Well, since you are following a tutorial, I have no idea if they also wrote a db class and made it available for download or not. But if you had downloaded it, I'd assume you'd know where it is. So, either go back and see if there is such a file to download, or write your own db class. Where you put the file is up to you. Just bear in mind that the webserver may be configured not to allow file access above the web root. But if you don't put all files in the same directory, you'd need to add the path to the directory where you keep the class files in the autoload function.

To write your own db class, have a look at http://se2.php.net/manual/en/book.mysqli.php
A common approach to managing db connections is the singleton pattern (web search will certainly yield info on that), since you don't want to open new connections all the time. Generally, one connection per request is enough.

I'd skip the getInstance, and have the db class deal with the queries instead. Something along the lines of

class db {
	private static $mysqli = false;

// disallow class instantiation
private function __construct() {}

public static &function query($sql) {
	if (!self::$mysqli)
		self::$mysqli =  new mysqli('ip/localhost', 'user', 'pass', 'db schema');

	// add error handling to output/log errors if the connection failed

	$result = self::$mysqli->query($sql);
	// add error handling to output/log erros if the query failed

	return $result;
}

// deal with mysqli::prepare and execute in a similar way
}