PHP foreach导致＆＃34;为foreach（）提供的无效参数＆＃34;

Question

我有一个foreach循环，根据ACF转发器字段（map_destinations）的内容执行某些操作。如果有目的地，它可以正常工作，但如果我没有：

  

＆＃34;为foreach（）＆＃34;

提供的参数无效

这是我的代码：

$map_destinations = get_field('map_destinations', $tour_id);        
$map = array();
    foreach ($map_destinations as $map_destination) {
    $map[] = $map_destination['destination'];
}

我尝试了各种解决方案但没有工作。最普遍接受的方法似乎是：

$map_destinations = get_field('map_destinations', $tour_id);        
$map = array();
if (is_array($map)) {
    foreach ($map_destinations as $map_destination) {
    $map[] = $map_destination['destination'];
    }
}

我哪里错了？请耐心等待我，我只是要掌握php。

Answer 1

您不应该检查is_array($map)而是检查is_array($map_destinations)或!empty()

$map_destinations = get_field('map_destinations', $tour_id);        
$map = array();
if (is_array($map_destinations)) {
    foreach ($map_destinations as $map_destination) {
        $map[] = $map_destination['destination'];
    }
}