访问httpslavebfgdcomcnmediaeventget_listchnlid=4200000064得到数据： total 25 event_list event_id 215021138 str_event_id 000101030010040215021138 event_id 215021139 str_event_id 00010103001004021502113

可以使用以下PHP代码将数据内容的event_list内添加一个数组chnlid，值为请求接口的chnlid：

$data = '{
    "total": 25,
    "event_list": [{
        "event_id": 215021138,
        "str_event_id": "000101030010040215021138"
    }, {
        "event_id": 215021139,
        "str_event_id": "000101030010040215021139"
    }],
    "pf_prev_list": [],
    "chnl_modify_time": 1695089290,
    "fcc_switch": 1,
    "ret": 0,
    "request_id": "650a02adac124b1500007b80699654b4",
    "ret_msg": "success"
}';

$chnlid = "4200000064";

$data = json_decode($data, true);
foreach ($data["event_list"] as &$event) {
    $event["chnlid"] = $chnlid;
}

$result = json_encode($data);
echo $result;

输出结果为：

{
    "total": 25,
    "event_list": [
        {
            "event_id": 215021138,
            "str_event_id": "000101030010040215021138",
            "chnlid": "4200000064"
        },
        {
            "event_id": 215021139,
            "str_event_id": "000101030010040215021139",
            "chnlid": "4200000064"
        }
    ],
    "pf_prev_list": [],
    "chnl_modify_time": 1695089290,
    "fcc_switch": 1,
    "ret": 0,
    "request_id": "650a02adac124b1500007b80699654b4",
    "ret_msg": "success"
}

以上代码将原始数据解析为数组，然后使用foreach循环遍历event_list数组，并在每个event中添加一个键值对"chnlid"，值为请求接口的chnlid。最后将修改后的数组转换为JSON格式并输出。