无法从PHP类获得返回输出

Question

This is my code in my class

    <?php
class PerClass
{
    private $sql_connection = null;
    private $localAf = '9929292F';
    function __construct($env) {
        // Nasty globals, sorry
        global $_config;
    $host = "localhost";
    $user = "user";
    $pass = "pass";
    $db = "kModule";


        // Build sql connection
        $this->sql_connection = new mysqli($host, $user, $pass, $db);
        // Check connection
        if ($this->sql_connection->connect_error) {
            die("Connection failed: " . $this->sql_connection->connect_error);
        }
    }

    public function getOrders($sSettingsId) {
        $query = <<<SQL
            SELECT * FROM `scrub_order_log` WHERE `scrub_settings_id` = {$sSettingsId} AND `order_date` BETWEEN (NOW() - INTERVAL (SELECT `c_h_days` FROM `scrub_settings` WHERE `id` = {$sSettingsId}) DAY) AND NOW() ORDER BY `order_date` DESC;
SQL;
        $result = $this->sql_connection->query($query);
        $resp = null;
        while ($row = $result->fetch_assoc()) {
            $resp[] = $row;
        }
        return $resp;
    }
}
?>

I am trying to get the output as shown in code below

<?
$details = $PerClass->getOrders('1');
print_r($details);
?>

But unfortunately I am getting following erro

Fatal error: Call to a member function getOrders() on null in /home/domn/public_html/stage/stage_test.php on line 37

Tried different ways but I think I am doing something wrong

Answer 1

The code that calls the getOrders method is missing the object instantiation.

<?
    // add this here
    $PerClass = new PerClass();
    $details = $PerClass->getOrders('1');
    print_r($details);
?>

now, because the constructor method of your PerClass expects you to pass in a value as an argument, this is going to result in the following warning:

WARNING Missing argument 1 for PerClass::__construct()

In order to resolve this warning you have two options:

1. Pass the value of the $env parameter when you instantiate the object i.e. $PerClass = new PerClass('value_to_be_passed'); or
2. Get rid of the $env argument in your constructor since - from what I can see - it is not used anywhere i.e. from function __construct($env) { ... } to function __construct() { ... }.

See this link for an interested discussion about using global in PHP.