将文件以及一些参数发布到 web api

Question

我有 Web api 控制器 Uploads Controller，它有 PostUpload 方法将数据存储到数据库。

现在我正在尝试将文件和一些参数发布到该 Web api，但所有尝试都失败，例如通过数组列表、json 对象传递，我们不能将文件和参数发布到 Web api？

var request = new RestRequest("Uploads", Method.POST);
request.RequestFormat = DataFormat.Json;

request.AddHeader("Content-Type", "application/json");
request.AddFile("filename", Server.MapPath("/Images/137549014628194.R6MyHlYrIfIo3BWPIytG_height640.png"), "image/png");
request.AddFile("filename", Server.MapPath("/Images/137549014628194.R6MyHlYrIfIo3BWPIytG_height640.png"), "image/png");
request.AddFile("filename", Server.MapPath("/Images/137549014628194.R6MyHlYrIfIo3BWPIytG_height640.png"), "image/png");
request.AddParameter("participantsId", 2);
request.AddParameter("taskId", 77);
request.AddParameter("EnteredAnswerOptionId", 235);
IRestResponse response = createClient().Execute(request);

web api 方法：

[HttpPost]
public string PostUpload(int? participantsId, int? taskId, int? EnteredAnswerOptionId)
{
    var file = HttpContext.Current.Request.Files.Count > 0 ?
    HttpContext.Current.Request.Files[0] : null;
    if (file.ContentLength > 0)
    {
        var fileName = Path.GetFileName(file.FileName);
        var path = Path.Combine(HttpContext.Current.Server.MapPath("~/uploads"), fileName);
        file.SaveAs(path); 
    }
    return "/uploads/" + file.FileName;
}

但它给出的错误如下：

ExceptionMessage":"没有 MediaTypeFormatter 可用于从具有媒体类型的内容中读取类型为“xxxx”的对象 '多部分/表单数据

我需要将文件和参数发布到我的 api。

使用 restsharp 发送数据

Answer 1

我能够使用以下控制台应用程序成功发布（基于this post）：

    static void Main(string[] args)
    {
        RunAsync().Wait();
    }

    static async Task RunAsync()
    {
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://localhost:3963/");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            string filepath = "C:/Users/Popper/Desktop/Stackoverflow/MatchPositions.PNG";
            string filename = "MatchPositions.PNG";

            MultipartFormDataContent content = new MultipartFormDataContent();
            ByteArrayContent fileContent = new ByteArrayContent(System.IO.File.ReadAllBytes(filepath));
            fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = filename };
            content.Add(fileContent);

            HttpResponseMessage response = await client.PostAsync("api/Upload?participantsId=2&taskId=77&EnteredAnswerOptionId=235", content);
            string returnString = await response.Content.ReadAsAsync<string>();
        }
    }