PHP CURL如何支持传多维数组？

$_getData['test']['name']['ec'] = 'egeer';

//curl GET + POST 提交
public function filePostContents($url, $data) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_COOKIESESSION, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
    curl_setopt($ch, CURLOPT_TIMEOUT, 600);
    //curl_setopt($ch, CURLOPT_USERAGENT, _USERAGENT_);        
    //curl_setopt($ch, CURLOPT_REFERER,_REFERER_);        
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $r = curl_exec($ch);
    curl_close($ch);
    return $r;
}

http_build_query 这个函数只能支持到3维数组啊

写四维数组 $_getData['test']['name']['ec']['php'] = 'egeer';
就报错 Cannot use string offset as an array i