How to upload a document use this API

[Squallerxp]

Hello,

I try to use Document Import function from Microsoft Custom Translator API Preview 1.0 to upload a document to Customer Translator Protal but failed.

The API I use is below
/api/texttranslator/v1.0/documents/import
Upload files for processing. Documents are created asynchronously. Upload status can be checked using the returned job id
from https://custom-api.cognitive.microsofttranslator.com/swagger/#!/Documents/ApiTexttranslatorV1_0DocumentsImportPost

there is my code below,

    static void Main(string[] args)
    {
        client.LoadCredentials();
        clientId = AccessTokenClient.ClientId;

        ''' ''' '''

        // Get the categories from the Custom Translator api. This just tests that we have a valid auth token.
        Console.WriteLine("Calling Custom Translator categories API to verify auth...");
        restClient = new RestClient(apiEndpoint);
        GetCategories(idToken);

        string result = ComboFile(idToken);

        Console.WriteLine();
        Console.WriteLine($"Press any key to exit.");
        Console.ReadKey();
    }

    public static String ComboFile(string token)
    {
        string filepath = @"C:\test.xlsx";                                      // Enter local path for combo file
        DocumentDetailsForImportRequest documentdetails = new DocumentDetailsForImportRequest();
        documentdetails.DocumentName = Path.GetFileName(filepath);    // Enter document name
        documentdetails.DocumentType = "training";                              // values = training/ tuning/ testing
        documentdetails.IsParallel = false;                                     // Enter if this is a parallel document. values = true, false
        documentdetails.FileDetails = new List<FileForImportRequest>();
        string result = ImportComboDocument("Bearer " + token, workspaceId, filepath, documentdetails);
        return result;
    }

    public static string ImportComboDocument(string authtoken, string workspaceid, string filepath, DocumentDetailsForImportRequest documentdetails)
    {
        string result = "";
        string host = "https://custom-api.cognitive.microsofttranslator.com";   // prod
        string apipath = $"/api/texttranslator/v1.0/documents/import?workspaceId={Uri.EscapeUriString(workspaceid)}";
        FileForImportRequest combofile = new FileForImportRequest();
        combofile.Name = Path.GetFileName(filepath);
        combofile.OverwriteIfExists = false;
        //combofile.Language = "";
        //combofile.Type = "";

        documentdetails.FileDetails.Add(combofile);
        var details = new List<DocumentDetailsForImportRequest>() { documentdetails };
        HttpClient client = new HttpClient();
        client.DefaultRequestHeaders.Add("Authorization", authtoken);
        string uri = host + apipath;

        HttpResponseMessage response = new HttpResponseMessage();
        MultipartFormDataContent formData = new MultipartFormDataContent();

        FileStream targetlanguagestream = File.OpenRead(filepath);
        HttpContent targetfileStreamContent = new StreamContent(targetlanguagestream);
        formData.Add(targetfileStreamContent, "Files", combofile.Name);

        string stringdata = JsonConvert.SerializeObject(details, Formatting.Indented);
        StringContent stringcontent = new StringContent(stringdata);
        formData.Add(stringcontent, "DocumentDetails");

        try
        {
            response = client.PostAsync(uri, formData).Result;
            result = response.Content.ReadAsStringAsync().Result;
            response.EnsureSuccessStatusCode();
        }
        catch (Exception e)
        {
            result = e.Message + ". " + e.InnerException;
        }
        return result;
    }

after running
response = client.PostAsync(uri, formData).Result;
the response is
{StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
Transfer-Encoding: chunked
Access-Control-Expose-Headers: Location, Content-Disposition
Request-Context: appId=cid-v1:347e3f37-b249-4148-861e-bcb47f147755
Strict-Transport-Security: max-age=31536000
X-Content-Type-Options: nosniff
api-supported-versions: 1.0
Date: Wed, 10 Mar 2021 08:09:19 GMT
Server: Kestrel
X-Powered-By: ASP.NET
Content-Type: application/json; charset=utf-8
}}

would you have any suggest on my issue, thanks.

there have two classes used for this document uploading

public class DocumentDetailsForImportRequest
{
    public string DocumentName { get; set; }
    public string DocumentType { get; set; } //values = training/ tuning/ testing
    public bool IsParallel { get; set; }
    public List<FileForImportRequest> FileDetails { get; set; }
}

public class FileForImportRequest
{
    public string Name { get; set; }
    public string Language { get; set; }
    public string Type { get; set; }
    public bool OverwriteIfExists { get; set; }
}

I want upload a combodocument,
How can I set the values for FileForImportRequest.Language and FileForImportRequest.Type.

Thanks.