如何在使用CodeIgniter制作的API中记录变量

我正在远程调试以前的程序员使用CodeIgniter框架构建的API。我用其他PHP MVC框架编程，但我以前从未构建过API(也没有使用CodeIgniter)，并且调试变量总是像echo， var_dump， print_r一样容易，……或者直接使用框架的日志命令。

现在，我没有显示错误和日志的页面(或者我有吗?)，我尝试了log_message， error_log和put_file_contents，没有任何运气!它只运行第一个日志命令，但第二个不运行!

在我的模型我有以下功能:

public function processcontacts($data) {
        error_log(json_encode($data), 3, "~/logs/processcontacts_data.txt");
        $countryCode = $data["countryCode"];
        error_log(json_encode($countryCode), 3, "~/logs/processcontacts_countryCode.txt");
        $isContact = array();
        $isNotContact = array();
        foreach ($data as $key => $value) {
                $value->phone = str_replace(" ", "", $value->phone);
                $value->name = str_replace(" undefined", "", $value->name);
                $value->name = str_replace(" Undefined", "", $value->name);
                $query = $this->db->get_where('appusers', array(
                    'id' => $this->getMyId($value->phone, $countryCode)
                        )
                );
                if ($query->num_rows() > 0) {
                    $row = $query->row();
                    $value->country = $row->country;
                    if ($row->photoapproved == 1) {
                        $value->photo = $row->photo;
                    }
                    $value->token = $row->token;
                    array_push($isContact, $value);
                } else {
                    array_push($isNotContact, $value);
                }
            }
        $returner = array();
        $returner["isMember"] = $isContact;
        $returner["isNotMember"] = $isNotContact;
        return json_encode($returner);
    }

我有两个error_log(或put_file_contents)，但只有一个显示，之后什么也没有!任何可能的是什么可能是这个原因和如何跟踪它?

/*
|--------------------------------------------------------------------------
| Error Logging Threshold
|--------------------------------------------------------------------------
|
| You can enable error logging by setting a threshold over zero. The
| threshold determines what gets logged. Threshold options are:
|
|   0 = Disables logging, Error logging TURNED OFF
|   1 = Error Messages (including PHP errors)
|   2 = Debug Messages
|   3 = Informational Messages
|   4 = All Messages
|
| You can also pass an array with threshold levels to show individual error types
|
|   array(2) = Debug Messages, without Error Messages
|
| For a live site you'll usually only enable Errors (1) to be logged otherwise
| your log files will fill up very fast.
|
*/
$config['log_threshold'] = 4;