How to submit a multipart/form-data HTTP POST request from C#

Question

What is the easiest way to submit an HTTP POST request with a multipart/form-data content type from C#? There has to be a better way than building my own request.

T

Answer 1

I have not tried this myself, but there seems to be a built-in way in C# for this (although not a very known one apparently...):

private static HttpClient _client = null;

private static void UploadDocument()
{
    // Add test file 
    var httpContent = new MultipartFormDataContent();
    var fileContent = new ByteArrayContent(File.ReadAllBytes(@"File.jpg"));
    fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
    {
        FileName = "File.jpg"
    };

    httpContent.Add(fileContent);
    string requestEndpoint = "api/Post";

    var response = _client.PostAsync(requestEndpoint, httpContent).Result;

    if (response.IsSuccessStatusCode)
    {
        // ...
    }
    else
    {
        // Check response.StatusCode, response.ReasonPhrase
    }
}

Try it out and let me know how it goes.

Cheers!