使用 HTTPBwebRequest 调用 IBM Watson Discovery AddDocument API

Question

我需要将 Watson Discovery 功能集成到使用 Visual Studio 2015 Framework 4.5 开发的现有 Windows Service 应用程序中。

我们无法升级框架版本，因此 NuGet 库 ibm.Watson 无法正常工作。

我尝试转换此 curl 命令

curl -X POST -u "{username}":"{password}" -F "file=@c:temp1.json" https://gateway-fra.watsonplatform.net/discovery/api/v1/environments/{environment}/collections/{collection}/documents?version=2017-11-07

到 C# 代码中：

void test
{
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
string username = "{username}";
string password = "{password}";
string postData = File.ReadAllText(@"c:temp1.json");
string BASE_URL = "https://gateway-fra.watsonplatform.net/discovery/api/";
string url = BASE_URL + "/v1/environments/{environment}/collections/{collection}/documents";
var request = (HttpWebRequest)WebRequest.Create(url);
var data = Encoding.ASCII.GetBytes(postData);
request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = data.Length;
request.Credentials = new NetworkCredential(username, password);
using (var stream = request.GetRequestStream())
{
stream.Write(data, 0, data.Length);
}
var response = (HttpWebResponse)request.GetResponse();
var responseString = new  StreamReader(response.GetResponseStream()).ReadToEnd();
catch (WebException wex)
{
HttpWebResponse oHttpWebResponse = (HttpWebResponse)wex.Response;
Encoding oEncoding = Encoding.GetEncoding(1252);
string sEx = string.Empty;
using (StreamReader oStreamReader = new StreamReader(oHttpWebResponse.GetResponseStream(), oEncoding))
{
sEx = oStreamReader.ReadToEnd();
oStreamReader.Close();
}
System.Diagnostics.Debug.WriteLine(sEx);
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.ToString());
}
}

但是得到这个错误：

{
"code": 400,
"error": "The request does not contain a "file" part or "metadata" part. Include at least one of those parts and resubmit your request."
}

向请求添加文件或元数据的方法是什么？

Answer 1

这对我有用：

async Task<string> Upload()
{
string environmentId = "xxx";
string collectionId = "xxx";
string username = "xxx";
string password = "xxx";
string sResult = string.Empty;
string filename = @"c:tempwatson2824.json";
string url = $"https://gateway-fra.watsonplatform.net/discovery/api/v1/environments/{environmentId}/collections/{collectionId}/documents?version=2018-08-01";
FileStream fileStream = new FileStream(filename, FileMode.Open);
HttpContent fileStreamContent = new StreamContent(fileStream);
var credentials = new NetworkCredential(username, password);
var handler = new HttpClientHandler { Credentials = credentials };
using (var client = new HttpClient(handler))
{
using (var formData = new MultipartFormDataContent())
{
formData.Add(fileStreamContent, "file", filename);
var response = await client.PostAsync(url, formData);
if (response.IsSuccessStatusCode)
{
Stream oStream = await response.Content.ReadAsStreamAsync();
using (var reader = new StreamReader(oStream))
{
sResult = reader.ReadToEnd();
reader.Close();
}
}
}
}
fileStream.Close();
return sResult;
}