根据Google API距离（usort）从数据库中排序数组

Question

I get the address and the name from the database and I want to sort the results based on the distance that is being calculated by Google Maps API after it gets the destination from a query. It currently displays the following error messages 4 times (repeating them):

Warning: Illegal string offset 'routes' in C:\xampp\htdocs\app2\test.php on line 36

Warning: Illegal string offset 'legs' in C:\xampp\htdocs\app2\test.php on line 36

Warning: Illegal string offset 'distance' in C:\xampp\htdocs\app2\test.php on line 36

Warning: Illegal string offset 'text' in C:\xampp\htdocs\app2\test.php on line 36 

The printed array is displayed after the errors and it looks like this:

Array ( [0] => 0.3 km [1] => 1.7 km ) 

I want the result to be Name ($row['name']) and number of kms, all sorted in an ascending order based on kms. How should my usort look in order to achieve this? Or is there a problem somewhere else?

Here's my code:

<?php
require_once 'includes/session.php';
require_once 'includes/config.php';
require_once 'includes/design_query.php';
include_once 'includes/header.php';
include_once 'includes/menu.php';

//$origin = $_COOKIE['origin'];
//$id=$_GET['id'];

$origin = "Bucuresti+Avrig+30";
$id = 3;
$query = ("SELECT * FROM locations WHERE category_id='$id'");
$result = mysql_query($query) or die (mysql_error());
while($row = mysql_fetch_array($result))
{
$address = $row['Judet'] . '+' . $row['Localitate'] . '+' . $row['Strada'] . '+' . $row['Numar'];
$address = str_replace(' ', '+', $address);

$fullurl = 'http://maps.googleapis.com/maps/api/directions/json?origin=' . $origin . '&destination=' . $address .  '&alternatives=true&sensor=true';
$json_a = json_decode((file_get_contents($fullurl)),true); 

asort($row);

//echo $row['name'];
//echo "<span class='badge'>" . $json_a['routes'][0]['legs'][0]['distance']['text'] . "</span></button>";

$whole_data[] = $json_a['routes'][0]['legs'][0]['distance']['text'];
}

 function cmp($a, $b)
    {
        if ($a['routes'][0]['legs'][0]['distance']['text'] == $b['routes'][0]['legs'][0]['distance']['text']) {
            return 0;
        }
        return ($a['routes'][0]['legs'][0]['distance']['text'] < $b['routes'][0]['legs'][0]['distance']['text']) ? -1 : 1;
    }

    $a = array(3, 2, 5, 6, 1);

    usort($whole_data, "cmp");

    print_r($whole_data);

include_once 'includes/footer.php';
include_once 'includes/scripts.php';
?>

Answer 1

First of all let me just say that this code is a mess! Seeing the commented line where id is obtained from GET also makes it pretty clear that it will be prone to sql injection.

Anyway here is an attempt to make it do what you want (just important parts):

while($row = mysql_fetch_array($result))
{
$address = $row['Judet'] . '+' . $row['Localitate'] . '+' . $row['Strada'] . '+' . $row['Numar'];
$address = str_replace(' ', '+', $address);

$fullurl = 'http://maps.googleapis.com/maps/api/directions/json?origin=' . $origin . '&destination=' . $address .  '&alternatives=true&sensor=true';
$json_a = json_decode((file_get_contents($fullurl)),true); 



$whole_data[] = array("name" => $row["name"], "value" => $json_a['routes'][0]['legs'][0]['distance']['value'],  "text" => $json_a['routes'][0]['legs'][0]['distance']['text']);
}

 function cmp($a, $b)
    {
        if ($a['value'] == $b['value']) {
            return 0;
        }
        return ($a['value'] < $b['value']) ? -1 : 1;
    }


    usort($whole_data, "cmp");
// example print
foreach($whole_data as $row){
    echo "$row[name] $row[text] <br/>";
}