如何为 multipart/form-data 设置 Web API 控制器

Question

我正在努力解决这个问题。我的代码没有收到任何有用的错误消息，所以我使用了其他东西来生成一些东西。我在错误消息后附加了该代码。我在上面找到了一个 tutorial 但我不知道如何用我现有的实现它。这是我目前拥有的：

public async Task<object> PostFile()
    {
        if (!Request.Content.IsMimeMultipartContent())
            throw new Exception();


        var provider = new MultipartMemoryStreamProvider();
        var result = new { file = new List<object>() };
        var item = new File();

        item.CompanyName = HttpContext.Current.Request.Form["companyName"];
        item.FileDate = HttpContext.Current.Request.Form["fileDate"];
        item.FileLocation = HttpContext.Current.Request.Form["fileLocation"];
        item.FilePlant = HttpContext.Current.Request.Form["filePlant"];
        item.FileTerm = HttpContext.Current.Request.Form["fileTerm"];
        item.FileType = HttpContext.Current.Request.Form["fileType"];

        var manager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(new ApplicationDbContext()));
        var user = manager.FindById(User.Identity.GetUserId());

        item.FileUploadedBy = user.Name;
        item.FileUploadDate = DateTime.Now;

        await Request.Content.ReadAsMultipartAsync(provider)
         .ContinueWith(async (a) =>
         {
             foreach (var file in provider.Contents)
             {
                 if (file.Headers.ContentLength > 1000)
                 {
                     var filename = file.Headers.ContentDisposition.FileName.Trim('\"');
                     var contentType = file.Headers.ContentType.ToString();
                     await file.ReadAsByteArrayAsync().ContinueWith(b => { item.FilePdf = b.Result; });
                 }


             }


         }).Unwrap();

        db.Files.Add(item);
        db.SaveChanges();
        return result;

    }

错误：

Object {message: "The request entity's media type 'multipart/form-data' is not supported for this resource.", exceptionMessage: "No MediaTypeFormatter is available to read an obje…om content with media type 'multipart/form-data'.", exceptionType: "System.Net.Http.UnsupportedMediaTypeException", stackTrace: " at System.Net.Http.HttpContentExtensions.ReadAs…atterLogger, CancellationToken cancellationToken)"}exceptionMessage: "No MediaTypeFormatter is available to read an object of type 'HttpPostedFileBase' from content with media type 'multipart/form-data'."exceptionType: "System.Net.Http.UnsupportedMediaTypeException"message: "The request entity's media type 'multipart/form-data' is not supported for this resource."stackTrace: " at System.Net.Http.HttpContentExtensions.ReadAsAsync[T](HttpContent content, Type type, IEnumerable1 formatters, IFormatterLogger formatterLogger, CancellationToken cancellationToken) ↵ at System.Net.Http.HttpContentExtensions.ReadAsAsync(HttpContent content, Type type, IEnumerable1 formatters, IFormatterLogger formatterLogger, CancellationToken cancellationToken)

用于生成错误消息的代码：

    [HttpPost]
    public string UploadFile(HttpPostedFileBase file)
    {

        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;
    }

Class:

public class File
{
    public int FileId { get; set; }
    public string FileType { get; set; }
    public string FileDate { get; set; }
    public byte[] FilePdf { get; set; }
    public string FileLocation { get; set; }
    public string FilePlant { get; set; }
    public string FileTerm { get; set; }
    public DateTime? FileUploadDate { get; set; }
    public string FileUploadedBy { get; set; }

    public string CompanyName { get; set; }
    public virtual ApplicationUser User { get; set; }
}

Answer 1

我通常只在 Mvc Controllers 中使用 HttpPostedFileBase 参数。在处理 ApiControllers 时，请尝试检查传入文件的 HttpContext.Current.Request.Files 属性：

[HttpPost]
public string UploadFile()
{
    var file = HttpContext.Current.Request.Files.Count > 0 ?
        HttpContext.Current.Request.Files[0] : null;

    if (file != null && file.ContentLength > 0)
    {
        var fileName = Path.GetFileName(file.FileName);

        var path = Path.Combine(
            HttpContext.Current.Server.MapPath("~/uploads"),
            fileName
        );

        file.SaveAs(path);
    }

    return file != null ? "/uploads/" + file.FileName : null;
}

Answer 2

你可以使用这样的东西

[HttpPost]
public async Task<HttpResponseMessage> AddFile()
{
    if (!Request.Content.IsMimeMultipartContent())
    {
        this.Request.CreateResponse(HttpStatusCode.UnsupportedMediaType);
    }

    string root = HttpContext.Current.Server.MapPath("~/temp/uploads");
    var provider = new MultipartFormDataStreamProvider(root);
    var result = await Request.Content.ReadAsMultipartAsync(provider);

    foreach (var key in provider.FormData.AllKeys)
    {
        foreach (var val in provider.FormData.GetValues(key))
        {
            if (key == "companyName")
            {
                var companyName = val;
            }
        }
    }

    // On upload, files are given a generic name like "BodyPart_26d6abe1-3ae1-416a-9429-b35f15e6e5d5"
    // so this is how you can get the original file name
    var originalFileName = GetDeserializedFileName(result.FileData.First());

    var uploadedFileInfo = new FileInfo(result.FileData.First().LocalFileName);
    string path = result.FileData.First().LocalFileName;

    //Do whatever you want to do with your file here

    return this.Request.CreateResponse(HttpStatusCode.OK, originalFileName );
}

private string GetDeserializedFileName(MultipartFileData fileData)
{
    var fileName = GetFileName(fileData);
    return JsonConvert.DeserializeObject(fileName).ToString();
}

public string GetFileName(MultipartFileData fileData)
{
    return fileData.Headers.ContentDisposition.FileName;
}

Answer 3

检查你的 WebApiConfig 并添加这个

GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();

Answer 4

您收到 HTTP 415 "The request entity's media type 'multipart/form-data' is not supported for this resource." 因为您没有在请求中提及正确的内容类型。

Answer 5

这就是解决我问题的方法
将以下行添加到 WebApiConfig.cs

config.Formatters.XmlFormatter.SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("multipart/form-data"));

Answer 6

也许聚会迟到了。但是还有一个替代解决方案是使用 ApiMultipartFormFormatter 插件。

此插件可帮助您像 ASP.NET Core 一样接收 multipart/formdata 内容。

在github页面中，已经提供了demo

Answer 7

5 年后，.NET Core 3.1 允许您像这样指定媒体类型：

[HttpPost]
[Consumes("multipart/form-data")]
public IActionResult UploadLogo()
{
    return Ok();
}

Answer 8

这是 ASP.Net 这个问题的核心解决方案的另一个答案...

在 Angular 方面，我采用了这个代码示例...

https://stackblitz.com/edit/angular-drag-n-drop-directive

... 并将其修改为调用 HTTP Post 端点：

  prepareFilesList(files: Array<any>) {

    const formData = new FormData();
    for (var i = 0; i < files.length; i++) { 
      formData.append("file[]", files[i]);
    }

    let URL = "https://localhost:44353/api/Users";
    this.http.post(URL, formData).subscribe(
      data => { console.log(data); },
      error => { console.log(error); }
    );

有了这个，下面是我在 ASP.Net 核心 WebAPI 控制器中需要的代码：

[HttpPost]
public ActionResult Post()
{
  try
  {
    var files = Request.Form.Files;

    foreach (IFormFile file in files)
    {
        if (file.Length == 0)
            continue;
        
        string tempFilename = Path.Combine(Path.GetTempPath(), file.FileName);
        System.Diagnostics.Trace.WriteLine($"Saved file to: {tempFilename}");

        using (var fileStream = new FileStream(tempFilename, FileMode.Create))
        {
            file.CopyTo(fileStream);
        }
    }
    return new OkObjectResult("Yes");
  }
  catch (Exception ex)
  {
    return new BadRequestObjectResult(ex.Message);
  }
}

非常简单，但我必须从几个（几乎正确的）来源拼凑示例才能使其正常工作。

Answer 9

我就是这样工作的，希望对你有帮助！

        [HttpPost("AddProduct")]

        public async Task<IActionResult> AddProduct( IFormFile files)
        {
            string fileGuid = Guid.NewGuid().ToString();
            var pathImage = Path.Combine(_hostEnvironment.ContentRootPath, "Images", fileGuid);
            var streamImage = new FileStream(pathImage, FileMode.Append);
            await files.CopyToAsync(streamImage);

            return Ok();

           
        }

如何为 multipart/form-data 设置 Web API 控制器

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