如何通过多维数组的键递归搜索？

I am trying to create a recursive function that takes an array and looks for a property name children, and constructs an array out of the matching one.

This is not straight forward because I don't know which block of my JSON data will contain the key children, so I decided to write a recursive function.

I've tried

$testDataJson = '
{
    "macAddress": "10:20:30:40:50:81",
    "type": "HGW",
    "children": [{
        "macAddress": "98:D6:D6:D8:FF:34",
        "pendingMethods": false,
        "lastSeen": "2017-05-24T10:36:35",
        "lastSeenLight": "GREEN",
        "model": "AP7465CE-TN",
        "type": "WIRELESS_ACCESS_POINT"
    }, {
        "macAddress": "44:66:E9:A1:2C:DC",
        "pendingMethods": false,
        "lastSeen": "2017-05-24T10:39:01",
        "lastSeenLight": "GREEN",
        "model": "PLC 200+ DIV -TN",
        "type": "POWERLINE"
    }, {
        "macAddress": "D8:C2:A9:1C:44:47",
        "pendingMethods": "False",
        "lastSeen": "2017-05-24T10:39:01",
        "lastSeenLight": "GREEN",
        "model": "PG9073",
        "type": "POWERLINE",
        "children": [{
            "macAddress": "22:CD:E6:8F:8C:B8",
            "pendingMethods": false,
            "lastSeen": "2017-05-24T10:38:16",
            "lastSeenLight": "GREEN",
            "model": "PG9073",
            "type": "POWERLINE"
        }, {
            "macAddress": "13:E4:AB:33:36:AC",
            "pendingMethods": false,
            "lastSeen": "2017-05-24T10:29:13",
            "lastSeenLight": "GREEN",
            "model": "PG9072",
            "type": "POWERLINE_WIRELESS_ACCESS_POINT"
        }]
    }]
}';
$testDataArray = json_decode($testDataJson,true);

function recursiveKeyFinder($array) {
    $result = [];
    if (!isset($array['children']) AND is_array($array)) {
       return $result;
    }else {
        foreach($array['children'] as $child){
            $result['macAddress'] = $child['macAddress'];
        }
        return recursiveKeyFinder($array);
    }
}
var_dump(recursiveKeyFinder($testDataArray));

Result: Nothing from var_dump().

Desired result:

["macAddress": "98:D6:D6:D8:FF:34",
"macAddress": "44:66:E9:A1:2C:DC",
"macAddress": "D8:C2:A9:1C:44:47",
"macAddress": "22:CD:E6:8F:8C:B8",
"macAddress": "13:E4:AB:33:36:AC"]

Any hints/suggestions / helps on this be will be much appreciated!

Like Barmar siad "You have infinite recursion."

This is my solution. It prints out all mac address

function recursiveKeyFinder($array) {
    $result = [];

    $result[] = $array['macAddress'];
    if (isset($array['children'])) {
        foreach($array['children'] as $child){
            $result = array_merge($result,recursiveKeyFinder($child));
        }
    }
    return $result;
}

Here the result

array (size=6)
  0 => string '10:20:30:40:50:81' (length=17)
  1 => string '98:D6:D6:D8:FF:34' (length=17)
  2 => string '44:66:E9:A1:2C:DC' (length=17)
  3 => string 'D8:C2:A9:1C:44:47' (length=17)
  4 => string '22:CD:E6:8F:8C:B8' (length=17)
  5 => string '13:E4:AB:33:36:AC' (length=17)

Hope this can help

PHP already offers a specific tool for this operation: array_walk_recursive(); so there is no need to reinvent the wheel.

Your task can be swiftly, concisely completed with just one function call after preparing your json data.

Omitting the first macAddress (unwanted) value is done by passing only the subarray with the key of 'children' to array_walk_recursive().

Code: (Demo)

$array=json_decode($testDataJson,true)['children'];  // this avoids including the first "non-children" macAddress value.
array_walk_recursive($array,function($v,$k)use(&$result){if($k==='macAddress') $result[]=$v;});
var_export($result);

Result:

array (
  0 => '98:D6:D6:D8:FF:34',
  1 => '44:66:E9:A1:2C:DC',
  2 => 'D8:C2:A9:1C:44:47',
  3 => '22:CD:E6:8F:8C:B8',
  4 => '13:E4:AB:33:36:AC',
)

Alternatively, the input array can be prepared like this:

$array=array_diff_key(json_decode($testDataJson,true),['macAddress'=>'']);

This will ensure you don't accidentally grab any non-children macAddress values.