我正在尝试使用 CURL 通过“从文件 API 调用创建文档”将文件发送到 PANDADOCS：https://developers.pandadoc.com/reference/create-document-from-pdf。

除了发送文件之外，我还需要发送一个包含收件人等的数据对象，作为 multipart/form-data 字符串的一部分以 JSON 形式发送。我不确定如何正确设置此调用，并且不断收到从其 API 返回的各种错误消息，例如“存在名为文件的字段”

这是我到目前为止所拥有的：

public function createDocument()
    {


        $p = getmypid();
        $m = "({$p}): PandaDoc::create document: ";


        $postfields         = array();
        $postfields['name'] = $this->document->name;
        $postfields['file']  = $this->document->file; //base 64 encoded PDF

        $recipients = array(
            array(
                'email'      => 'a.mcdoogle@test.com',
                'first_name' => 'Andrew',
                'last_name'  => 'Mcdoogle',
                'role'       => 'user',
                'signing_order' => 1
            )
        );


        $data = array();
        $data['recipients'] = $recipients;

        $owner = array(
            "email" => "john@example.com"
        );

        $data['owner'] = $owner;

        $postfields['data'] =  json_encode($data);

        $header = array("Authorization: API-Key {$this->api_key}", "Content-Type: multipart/form-data", "accept" => "application/json");

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
        curl_setopt($ch, CURLOPT_URL, $this->url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $postfields);


        $res = curl_exec($ch);

        if ($res === false) {
            $errno = curl_errno($ch);
            $error = curl_error($ch);
            error_log("{$m}cURL error: {$error} ({$errno})");
            throw new Exception("{$m}cURL error: {$error} ({$errno})");
        }

        $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

        curl_close ($ch);

        error_log("{$m}Results from PandaDoc: {$res}");

        $response = json_decode($res);

        return $response;

    }

谁能告诉我我做错了什么？