PHP foreach 导致“foreach() 提供的参数无效”[重复]

Question

我有一个 foreach 循环，它根据 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，但如果没有，我会得到：

“为 foreach() 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，但都没有奏效。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？请多多包涵，我刚刚开始掌握 php。

Answer 1

您不应检查is_array($map)，而应检查is_array($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'];
    }
}