How to send a file and form data with HttpClient in C#

How can I send a file and form data with the HttpClient?

I have two ways to send a file or form data. But I want to send both like an HTML form. How can I do that? Thanks.

This is my code:

if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
    var client = new HttpClient();
    var requestContent = new MultipartFormDataContent();
    filename = openFileDialog1.FileName;
    array = File.ReadAllBytes(filename);
    var imageContent = new ByteArrayContent(array);
    imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("audio/*");
    requestContent.Add(imageContent, "audio", "audio.wav");
    var values = new Dictionary<string, string>
    {
        { "token", "b53b99534a137a71513548091271c44c" },
    };
    var content = new FormUrlEncodedContent(values);
    requestContent.Add(content);
    var response = await client.PostAsync("localhost", requestContent);
    var responseString = await response.Content.ReadAsStringAsync();
    txtbox.Text = responseString.ToString();
}

Here's code I'm using to post form information and a csv file

using (var httpClient = new HttpClient())
{
    var surveyBytes = ConvertToByteArray(surveyResponse);

    httpClient.DefaultRequestHeaders.Add("X-API-TOKEN", _apiToken);
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var byteArrayContent =   new ByteArrayContent(surveyBytes);
    byteArrayContent.Headers.ContentType = MediaTypeHeaderValue.Parse("text/csv");

    var response = await httpClient.PostAsync(_importUrl, new MultipartFormDataContent
    {
        {new StringContent(surveyId), "\"surveyId\""},
        {byteArrayContent, "\"file\"", "\"feedback.csv\""}
    });

    return response;
}

This is for .net 4.5.

Note the \" in the MultipartFormDataContent. There is a bug in MultipartFormDataContent.

In 4.5.1 MultipartFormDataContent wraps the data with the correct quotes.

Update: This link to the bug no longer works since the have retired Microsoft Connect.

Here's code I'm using a method to send file and data from console to API

               
static async Task uploaddocAsync()
{
    MultipartFormDataContent form = new MultipartFormDataContent();
    Dictionary<string, string> parameters = new Dictionary<string, string>();
    //parameters.Add("username", user.Username);
    //parameters.Add("FullName", FullName);
    HttpContent DictionaryItems = new FormUrlEncodedContent(parameters);
    form.Add(DictionaryItems, "model");

    try
    {
        var stream = new FileStream(@"D:\10th.jpeg", FileMode.Open);
        HttpClient client = new HttpClient();
        client.BaseAddress = new Uri(@"http:\\xyz.in");
            
        HttpContent content = new StringContent("");
        content.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
        {
            Name = "uploadedFile1",
            FileName = "uploadedFile1"
        };
        content = new StreamContent(stream);
        form.Add(content, "uploadedFile1"); 

        client.DefaultRequestHeaders.Add("Authorization", "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.dsfdsfdsfdsfsdfkhjhjkhjk.vD056hXETFMXYxOaLZRwV7Ny1vj-tZySAWq6oybBr2w");
                 
        var response = client.PostAsync(@"\api\UploadDocuments\", form).Result;
        var k = response.Content.ReadAsStringAsync().Result;
    }
    catch (Exception ex)
    {


    }
}