c# - .NET Core API List 文件未从 .NET MVC MultipartFormDataContent POST 接收

Question

我在下面有一个 .NET Core API POST 方法:

    public IActionResult UploadFiles([FromForm(Name = "files")] List<IFormFile> files, [FromForm(Name = "providerName")] string providerName) 
    {
        try
        {
            return WriteToXlsx(files,providerName); //documents
        }
        catch (Exception ex)
        {

            return BadRequest($"Error: {ex.Message}");
        }
    }

从 postman 发帖时工作正常，收到文件。
但是，当尝试从 ASP.NET MVC 发布时，如下所示，似乎没有收到文件。没有错误消息，但列表文件中的文件计数为零。正在接收字符串“providerName”。

    [HttpPost]
    public async Task<ActionResult> ContentTransformation(IEnumerable<HttpPostedFileBase> files, string providerName)
    {
      
        try
        {
            HttpClientHandler clientHandler = new HttpClientHandler();
            var httpClient = new HttpClient(clientHandler);
            var multipartFormDataContent = new MultipartFormDataContent();

            foreach (HttpPostedFileBase file in files)
            {
                byte[] fileData;
                using (var reader = new BinaryReader(file.InputStream))
                {
                    fileData = reader.ReadBytes(file.ContentLength);
                }
                var fileContent = new ByteArrayContent(fileData);
                multipartFormDataContent.Add(fileContent, "files");
            }

            StringContent sProviderName = new StringContent(providerName);
            multipartFormDataContent.Add(sProviderName, "\"providerName\"");

            var response = await httpClient.PostAsync(ConfigurationManager.AppSettings["ContentTransformationAPI"], multipartFormDataContent);

            FileContentResult metadataContent = new FileContentResult(response.Content.ReadAsByteArrayAsync().Result, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");

            return File(
                fileContents: metadataContent.FileContents,
                contentType: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                fileDownloadName: "metadata.xlsx"
                );
        }
        catch (Exception ex)
        {

            ViewBag.Message = "File upload failed!! " + ex.Message;
            ModelState.Clear();
            return View();
        }
    }

Answer 1

编辑
我发现了问题。您正在丢弃 FileName上传，因此当您将数据从 MVC Controller 发布到 API Controller 时，它不会正确绑定(bind)。您需要更改的只是:

multipartFormDataContent.Add(fileContent, "files");

到

multipartFormDataContent.Add(fileContent, "files", file.FileName);

然后文件将被正确绑定(bind)。
旧答案
您的代码( Controller + 表单元素)对我有用，这让我认为您的表单设置不正确。在最简单的情况下，它应该如下所示:

@using (Html.BeginForm(
    "ContentTransformation", 
    "YourControllerName", // Make sure you change this.
    FormMethod.Post, 
    new { enctype = "multipart/form-data" }))
{
    <input type="file" name="files" multiple="multiple" />
    <input type="submit" />
}

我认为您可能缺少的部分是 new { enctype = "multipart/form-data" } . multipart/form-data enctype 允许输入元素上传文件数据，因此没有它您的上传器将无法工作。