如何将FormData发送到服务器

Question

你们能帮我把这个cURL转换成飞镖代码

curl --location --request POST'http：// prestao-service / leave / add'
--header'X-Auth-Token：dfd8d732-c066-463c-af4d-1a63e2f2b373'
--form'leave = {“ dateDemand”：1600732093584，“ dateStart”：1600732800000，“ dateEnd”：1601078400000，“ endDateDaySlot”：“ X”，“ startDateDaySlot”：“ X”，“ type”：“ CSS”} ' 我试过了，但是没用

 var request = new http.MultipartRequest("POST", uri);
    Map<String, String> heads = {
      "X-Auth-Token": UserPreferences().token,
      "Content-type": "multipart/form-data",
      "accept": "application/json"
    };
    request.headers.addAll(heads);
    request.fields['leave'] = json.encode({
      "dateDemand": 1600732093584,
      "dateStart": 1600732800000,
      "dateEnd": 1601078400000,
      "endDateDaySlot": "X",
      "startDateDaySlot": "X",
      "type": "CSS"
    });
    var response = await request.send();