HttpClient ContentDisposition Problem

[CavidH]

Hello friends, I encountered a problem when uploading a file, and I will share the code related to the issue below. When uploading a file using HttpClient, I use MultipartFormDataContent. When adding the file with the help of MultipartFormDataContent, the Content-Disposition appears as follows:
Content-Disposition: form-data; name=file; filename="=?utf-8?B?0YTQsNC50LsucG5n?="; filename*=utf-8''%D1%84%D0%B0%D0%B9%D0%BB.png
The reason is that the filename is in Russian. However, the server receiving the file does not support Content-Disposition in this format. I suggest that if the MultipartFormDataContent has both the Add method and the AddWithoutValidation method, our task becomes easier. Note: Currently, I have resolved this issue using WebRequest, but I would be very happy if it could be in a more modern format.

[HttpPost]
public async Task<IActionResult> FileUpload(IFormFile file)
{
    using HttpClient httpClient = new HttpClient();


    using var formData = new MultipartFormDataContent();
    formData.Add(new StreamContent(file.OpenReadStream()), "file", file.FileName);
    HttpResponseMessage response = await httpClient.PostAsync("https://example.com/upload-endpoint", formData);

    if (response.IsSuccessStatusCode)
    {
        //
    }
 
    return Ok(file.FileName);
}

[Qocali]

I have a good question. I will be happy if you answer

[MihaZupan]

If there is something about the format of the Content-Disposition header value that your server does not understand, you should be able to manually add the exact value format you want via the existing TryAddWithoutValidation method.

Something like

using var formData = new MultipartFormDataContent();
var fileContent = new StreamContent(myStream);
formData.Add(fileContent, "file", file.FileName);
fileContent.Headers.Remove("Content-Disposition");
fileContent.Headers.TryAddWithoutValidation("Content-Disposition", "the custom value that you've validated to be safe to use because it won't be validated further");

cc: @dotnet/ncl

[CavidH]

Thank you for your reply. I had already checked TryAddWithoutValidation but unfortunately, it didn't work as expected. I was hoping for it to work, but regrettably, I had to proceed with WebRequest.

[MihaZupan]

WebRequest is built on top of HttpClient (on .NET Core+), so if it is able to generate a value that your server is willing to accept, you should be able to mirror that with HttpClient.

[CavidH]

I had thought that HttpClient was built on top of WebRequest. I was mistaken. 😄

[CarnaViire]

I had thought that HttpClient was built on top of WebRequest

That was true for .NET Framework; on .NET Core/.NET 5+ it's the other way around 😄

[CavidH]

Got it, thank you for the information.