PHP Json解码对象存在

Question

如何从“gameid”存在且值为“730”的玩家那里获得所有“steamids”？ 它显示：
注意 未定义的属性：第 31 行的 stdClass::$gameid 因为“gameid”并不存在于每个元素中

代码：

$players = json_decode(file_get_contents("test.json"));
foreach($players->response->Players as $mydata)
{
if($players->gameid == "730"){
echo $mydata->steamid . "\n";
}

}   

我的 json：

{
    "response": {
        "players": [
            {
                "steamid": "76561198273176399",
                "loccountrycode": "US"
            },
            {
                "steamid": "76561198386141115",
                "gameid": "730",
                "loccountrycode": "DE"
            },
            {
                "steamid": "76561198019025166",
                "gameid": "730",
                "loccountrycode": "RU"
            },
            {
                "steamid": "76561198010529217",
                "loccountrycode": "DK"
            }
        ]

    }
}

非常感谢。致以最诚挚的问候。

Answer 1

改变

$players->response->Players
if($players->gameid == "730"){

到

$players->response->players // small letter "p"
if($mydata->gameid == "730"){

和$mydata->steamid一样

由于不是每个玩家都有gameid，所以最好也检查一下：

if( isset($mydata->gameid) && $mydata->gameid === '730' ) // or check on empty if the "gameid" can be set but also can be empty