Question

I have a method / function (in a class) that I am calling and I want to pass either and id or a url. The method then uses one of these arguments in a mysql WHERE query. It can only use one or the other.

How can I require one of two arguments? Or in other words how can I only make one of two arguments optional?

Is there a better way than to just make both arguments optional and use several if else statements?

Answer 1

If you want to literally require an argument:

public function fetchRow($where)
{
    if (empty($where['id']) && empty($where['url'])) {
        throw new Exception('WHERE clause must be supplied');
    }

    // proxy to specific method
    if (!empty($where['id'])) {
        return $this->fetchById((int) $where['id']);
    } elseif (!empty($url)) {
        return $this->fetchByUrl((string) $where['url']);
    }
}

public function fetchById($id) 
{
    if ($stmt = $mysqli->prepare('SELECT * FROM table WHERE id = ?')) {
        $stmt->bind_param('i', $id);
        // ...
    }
}

// ...
$object = new MyClass();
try {
    $object->fetchRow(); // would throw exception
    $object->fetchRow(array('id' => 10)); // would work
} catch (Exception $ex) {
    // do something, for example:
    echo $ex->getMessage(); // echoes 'at least one argument must be supplied'
}