PHP 获取数组父级的位置 - PHP get the position of a array parent

这里 a 有一个 json 字符串，需要获取 registratition_id 的所有父数组位置例如，我希望最后的数组放出这样的东西：

 [0] =>0
 [1] =>1
 [2] =>3

事实上，我想获取包含registration_id的所有数组位置

$json_raw = '{"multicast_id":6446899316497614986,
                     "success":5,
                     "failure":1,
                     "canonical_ids":3,
                     "results":[
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                               "message_id":"0:1396175384218906%50b5570df9fd7ecd"
                             },
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                              "message_id":"0:1396175384218155%50b5570df9fd7ecd"
                             },
                             {"message_id":"0:1396175384218718%b91f4d1ff9fd7ecd"
                             },
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                              "message_id":"0:1396175384219100%50b5570df9fd7ecd"
                             },
                             {"message_id":"0:1396175384219927%50b5570df9fd7ecd"
                             },
                             {"error":"InvalidRegistration"
                             }]
                       }';

使用 foreach 循环并检查是否registration_id isset

$obj = json_decode($json_raw);
$resultsWithRegID = array();
foreach($obj->results as $index=>$element){
  if(isset($element->registration_id)){
     $resultsWithRegID[] = $index;
  }
}

只是一个替代版本：

$array_raw = json_decode($json_raw, true);
$what = "registration_id";
$res = array_keys(array_filter($array_raw['results'], function($item) use ($what)
{
    return isset($item[$what]);
}));
var_dump($res);

显然，您可以：

定义键以直接在isset($item["registration_id"])内搜索
省略包装函数array_keys是否需要过滤数组的整个部分

（整部分）

array (size=3)
    0 => 
        array (size=2)
            'registration_id' => 'APA91bEgLFvrc0lnXqX3C1euQohdHrv...'
            'message_id' => ''
    1 => 
        array (size=2)
            'registration_id' => 'APA91bEgLFvrc0lnXqX3C1euQohdHrv...' 
            'message_id' => '0:1396175384218155%50b5570df9fd7ecd'
    3 =>
        array (size=2)
            'registration_id' => 'APA91bEgLFvrc0lnXqX3C1euQohdHrv...'
            'message_id' => '0:1396175384219100%50b5570df9fd7ecd'

<html>
<head>
<title>Online PHP Script Execution</title>
</head>
<body>
<?php
  $json_raw = '{"multicast_id":6446899316497614986,
                     "success":5,
                     "failure":1,
                     "canonical_ids":3,
                     "results":[
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                               "message_id":"0:1396175384218906%50b5570df9fd7ecd"
                             },
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                              "message_id":"0:1396175384218155%50b5570df9fd7ecd"
                             },
                             {"message_id":"0:1396175384218718%b91f4d1ff9fd7ecd"
                             },
                             {"registration_id":"APA91bEgLFvrc0lnXqX3C1euQohdHrv_wbxtGP86ezRzGWEVMQPpJjw1GMhGzfkI8Q34TU1KRts2j_-7CyU4ce6MlX5DB3umpXDGl-Ebmg53b44UKga79ee9Sal6gT_9rP3KIz9pDEUk2JVJsQmxiWXWoIfrYEAmFg",
                              "message_id":"0:1396175384219100%50b5570df9fd7ecd"
                             },
                             {"message_id":"0:1396175384219927%50b5570df9fd7ecd"
                             },
                             {"error":"InvalidRegistration"
                             }]
                       }';
$data=json_decode ($json_raw);
$arr= $data->{'results'};
$i=0;
$n_r=array();
foreach($arr as $d)
{$n_r[]=$arr[$i]->{'registration_id'};
$i=$i+1;}
print_r($n_r);
?>
</body>
</html>

将 JSON 转换为数组 - 其余的都是你的：

$array = json_decode($json_raw, true);
// results with registration_id
$results = array();
foreach($array['results'] as $index => $element) {
  if(isset($element['registration_id']) === true) {
     $results[] = $index;
  }
}
var_dump($results);