Generating form data for an API request

Question

Hi I am trying to write a C# client for this API: https://www.directdebit.co.za/api/dos.svc

On their endpoint for "/batch/eft/" they want me to send them a file with the formData Paramater Type. As far as I understand I should be using the MultipartContent class to do this. I've managed to read the file into a string variable, I just need to assign that to a multipart/formData paramater somehow. Here's my code so far:

    // Upload a file to Direct Debit via the API
    public async void UploadFile(string filePath)
    {
        if (!File.Exists(filePath))
        {
            throw new ArgumentException($"{filePath} does not exist");
        }

        var sb = new StringWriter();
        using (var fs = File.OpenRead(filePath))
        {
            var b = new byte[1024];
            while (fs.Read(b, 0, b.Length) > 0)
            {
                sb.Write(b);
            }
        }

        var content = sb.ToString();

        var hc = GenerateHttpClient();
        var postBody = new MultipartContent();

        // I am a little confused. What do I do now?

        var resp = await hc.PostAsync(url + "/batch/eft", postBody);
        resp.EnsureSuccessStatusCode();
    }

Thanks in advance.
Arie

Answer 1

I figured it out. I should have used MultipartFormDataContent, instead of just MultipartContent. The correct code is then:

        var postBody = new MultipartFormDataContent
        {
            {new ByteArrayContent(content.ToArray()), "file_data", Path.GetFileName(filePath)}
        };

        var resp = await hc.PostAsync(_url + "/batch/eft", postBody);

Answer 2

Thanks for posting the answer, I was also struggling with sending a file.