How to upload a photo to 500px using the BackgroundUploader in Windows Phone 8.1?

Question

I've got following code for uploading using OAuth.

public async Task UploadPhotoContinueAsync(IEnumerable<StorageFile> files)
{
    var uri = string.Format("https://api.500px.com/v1/photos/upload?name={0}&description={1}&privacy=0&category=0", "test name", "test description");
    var backgroudUploader = new BackgroundUploader();
    var headers = OAuthUtility.BuildBasicParameters(consumerKey, consumerSecret, uri, HttpMethod.Post, GetAccessToken());
    var header = string.Empty;
    var file = files.First();
    foreach (var item in headers)
    {
        header += string.Format(@"{0}=""{1}"",", item.Key, item.Value);
    }

    header = header.Remove(header.Length - 1);

    backgroudUploader.SetRequestHeader("Authorization", string.Format("OAuth {0}", header));
    backgroudUploader.SetRequestHeader("Filename", file.Name);

    var op = backgroudUploader.CreateUpload(new Uri(uri), file);
    try
    {
            var result = await op.StartAsync();
    }
    catch (Exception ex)
    {
        Debug.WriteLine(ex.Message);
    }
}

The problem is that everytime I start the operation I get a Internal Server Error from the API.

I can't seem to figure out what the problem is.

Did anybody figured this out? Thanks.

EDIT:

I finally made Fiddler work. Here are the headers that the app sends to the API:

Answer 1

I know it's not very professional, but I finally found a way to fix my code :)

Here's the updated function that works:

public async Task UploadPhotoContinueAsync(IEnumerable<StorageFile> files)
{
    var uri = string.Format("https://api.500px.com/v1/photos/upload?name={0}&description={1}&privacy=0&category=0", "test name", "test description");
    var backgroudUploader = new BackgroundUploader();
    var headers = OAuthUtility.BuildBasicParameters(consumerKey, consumerSecret, uri, HttpMethod.Post, GetAccessToken());
    var header = string.Empty;
    var file = files.First();
    foreach (var item in headers)
    {
        header += string.Format(@"{0}=""{1}"", ", item.Key, item.Value);
    }

    header = header.Remove(header.Length - 2);

    backgroudUploader.SetRequestHeader("Authorization", string.Format("OAuth {0}", header));
    backgroudUploader.SetRequestHeader("Filename", file.Name);
    string boundary = "----------------------------" + DateTime.Now.Ticks.ToString("x");
    backgroudUploader.SetRequestHeader("Content-Type", "multipart/form-data; boundary=" + boundary);
    backgroudUploader.Method = "POST";

    var parts = new List<BackgroundTransferContentPart>();
    var part = new BackgroundTransferContentPart();
    part.SetHeader("Content-Disposition", @"form-data; name=""file""; filename=""" + file.Name + "\"");
    part.SetFile(file);
    parts.Add(part);

    var op = await backgroudUploader.CreateUploadAsync(new Uri(uri), parts, "", boundary);
    try
    {
        var result = await op.StartAsync();
    }
    catch (Exception ex)
    {
        Debug.WriteLine(ex.Message);
    }
}

Thanks everyone that helped!