View from largest to smallest (php + json)

Question

Staff created a foreach to read a JSON result:

foreach($results['results']['collection1'] as $collection) {
echo $collection['nome'] . "<br />";
echo $collection['cat'] . "<br />";
echo $collection['nota'] . "<br />";
}

How do I make the results always appear from the highest to the lowest? Taking into account the key "note", it is she who will define the positions of the results.

Answer 1

Tested using the following test data:

// dados de teste
$results = array(
    'results' => array(
        'collection1' => array(
            array('nome' => 'a', 'cat' => '', 'nota' => 2),
            array('nome' => 'b', 'cat' => '', 'nota' => 1),
            array('nome' => 'c', 'cat' => '', 'nota' => 3),
            array('nome' => 'd', 'cat' => '', 'nota' => 4),
            array('nome' => 'e', 'cat' => '', 'nota' => 5),
            array('nome' => 'f', 'cat' => '', 'nota' => 6)
        )
    )
);

You want almost exactly the first example of http://php.net/manual/change.php?page=pt_BR%2Ffunction.usort.php :

// função de comparação
function compara_nota($a, $b) {
    if ($a['nota'] == $b['nota']) {
        return 0;
    }
    return ($a['nota'] > $b['nota']) ? -1 : 1;
}

usort($results['results']['collection1'], "compara_nota"); // ordena

foreach ($results['results']['collection1'] as $c) {
    echo $c['nome'] . "<br />";
    echo $c['cat'] . "<br />";
    echo $c['nota'] . "<br />";
}

If you do not want to modify the array that represents JSON, create another array:

$conjunto = $results['results']['collection1'];

// função de comparação
function compara_nota($a, $b) {
    if ($a['nota'] == $b['nota']) {
        return 0;
    }
    return ($a['nota'] > $b['nota']) ? -1 : 1;
}

usort($conjunto, "compara_nota"); // ordena

foreach ($conjunto as $c) {
    echo $c['nome'] . "<br />";
    echo $c['cat'] . "<br />";
    echo $c['nota'] . "<br />";
}

A more sophisticated example defining which key used in the call can be found in http://php.net/manual/change.php?page=en%2Ffunction.usort.php , example number 4, but the example shows only comparison of strings (only in the English version).