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I have a problem with the application sending the file to the web service. This is my endpoint/controller.

[HttpPost] public async Task<IActionResult> Post(List<IFormFile> files) { long size = files.Sum(f => f.Length); foreach (var formFile in files) { if (formFile.Length > 0) { var filePath = "C:\\Files\\TEST.pdf"; using (var stream = System.IO.File.Create(filePath)) { await formFile.CopyToAsync(stream); } } }

This controller works fine in Postman.

and this is my application that makes the request:

 byte[] bytes = System.IO.File.ReadAllBytes("C:\\Files\\files.pdf"); Stream fileStream = File.OpenRead("C:\\Files\\files.pdf"); HttpContent bytesContent = new ByteArrayContent(bytes); using (var client = new HttpClient()) using (var formData = new MultipartFormDataContent()) { formData.Add(bytesContent,"file", "files.pdf"); try { var response = await client.PostAsync(url, formData); }catch(Exception ex) { Console.WriteLine(ex); }

It doesn't work. I'm not receiving the file in controller. I also tried this:

 string fileToUpload = "C:\\Files\\files.pdf"; using (var client = new WebClient()) { byte[] result = client.UploadFile(url, fileToUpload); string responseAsString = Encoding.Default.GetString(result); }

but the result is the same. Would you be able to help?

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  • Do you have the logs available for us? Commented Sep 14, 2020 at 10:53
  • When calling the request "var response = await client.PostAsync (url, formData)" the program terminates, or calls the request which I receive in the controller but the ,,List<IFormFile> files" is null". It does not throw any exception. Looks like he's not sending the file. I don't know how to find out otherwise Commented Sep 14, 2020 at 11:01
  • When you are using HttpClient I bet you should also add some headers to request that will tell server that you are sending file. Check this answer stackoverflow.com/questions/42212406/… Commented Sep 14, 2020 at 11:10
  • For version with httpclient, the request is sent and not received by the controller. I do not know why Commented Sep 14, 2020 at 11:48

1 Answer 1

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Update 15/09/2020

This is the upload codes in ConsoleApplication. And it works with small file but not large file.

 public static async Task upload(string url) { //const string url = "https://localhost:44308/file/post"; const string filePath = "C:\\Files\\files.pdf"; try { using (var httpClient = new HttpClient{ Timeout = TimeSpan.FromSeconds(3600) }) { using (var form = new MultipartFormDataContent()) { using (var fs = System.IO.File.OpenRead(filePath)) { fs.Position = 0; using (var streamContent = new StreamContent(fs)) { form.Add(streamContent, "files", Path.GetFileName(filePath)); HttpResponseMessage response = httpClient.PostAsync(url, form).Result; fs.Close(); } } } } } catch (Exception e) { Console.WriteLine(e.Message); } }




There are two steps to fix your problem.

1.Add ContentType to Headers

bytesContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");

2. The file parameter name in formData should match action parameter name.

formData.Add(bytesContent,"file", "files.pdf"); //should be files public async Task<IActionResult> Post(List<IFormFile> files)

Update

HttpClient.PostAsync() doesn't work when awaited in Console Application. Instead of blocking with .Result, use .GetAwaiter().GetResult().

HttpResponseMessage response = httpClient.PostAsync(url, form).Result;


Here is the code to show how to upload file.

Codes of Controller

public class FileController : Controller { [HttpPost] public async Task<IActionResult> Post(List<IFormFile> files) { long size = files.Sum(f => f.Length); foreach (var formFile in files) { if (formFile.Length > 0) { var filePath = "C:\\Files\\TEST.pdf"; using (var stream = System.IO.File.Create(filePath)) { await formFile.CopyToAsync(stream); } } } return Ok(); } [HttpGet] public async Task<IActionResult> upload() { const string url = "https://localhost:44308/file/post"; const string filePath = @"C:\\Files\\files.pdf"; using (var httpClient = new HttpClient()) { using (var form = new MultipartFormDataContent()) { using (var fs = System.IO.File.OpenRead(filePath)) { using (var streamContent = new StreamContent(fs)) { using (var fileContent = new ByteArrayContent(await streamContent.ReadAsByteArrayAsync())) { fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data"); // "file" parameter name should be the same as the server side input parameter name form.Add(fileContent, "files", Path.GetFileName(filePath)); HttpResponseMessage response = await httpClient.PostAsync(url, form); } } } } } return Ok(); } }

Test

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5 Comments

Thank you for your answer!! I have one question. Because I am creating, a console application that uploads the file to the web service. On line ,,var fileContent = new ByteArrayContent(await streamContent.ReadAsByteArrayAsync()" the application ends and does not continue. The application does not throw exceptions. Why is this happening?
@Sebastian , HttpClient.PostAsync() doesn't work when awaited in Console Application. Try HttpResponseMessage response = httpClient.PostAsync(url, form).Result;, and it works on my ConsoleApp.
I want to accept the answer because it's great, but I'm having trouble with filestream. I have error ReadTimeout = 'file.ReadTimeout' threw an exception of type 'System.InvalidOperationException' WriteTimeout = 'file.WriteTimeout' threw an exception of type 'System.InvalidOperationException'. I don't know how to fix it in console application. It works great on the web service.
@Sebastian, I found that your issue is related with the size of file. I haven't deal with that and will keep on working it.
@Micheal Thank you! I deal with it. In postman I use C# RestSharp. Copy and paste, and everthing is all right

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