Parse push REST API error 400 "Bad Request" - ios

Question

I am developing an app for iOS using Xamarin iOS & MonoGame. I want to use Parse's push notifications through their REST API, so first I must create an installation object:
var bundle = new Dictionary<string, object>();
bundle.Add("channels", "");
bundle.Add("deviceType", "ios");
bundle.Add("deviceToken", _deviceToken);
string urlpath = "https://api.parse.com/1/installations";
var httpWebRequest = (HttpWebRequest)WebRequest.Create(urlpath);
httpWebRequest.ContentType = "application/json";
httpWebRequest.Headers.Add("X-Parse-Application-Id", _parseAppID);
httpWebRequest.Headers.Add("X-Parse-REST-API-KEY", _parseRestAPIKey);
httpWebRequest.Method = "POST";
string bundleString = bundle.ToJson();
byte[] buffer = Encoding.GetEncoding("UTF-8").GetBytes(bundleString);
string result = Convert.ToBase64String(buffer);
StreamWriter requestWriter = new StreamWriter(httpWebRequest.GetRequestStream());
requestWriter.Write(result, 0, result.Length);
requestWriter.Close();
WebResponse httpResponse = await httpWebRequest.GetResponseAsync();
Stream stream = httpResponse.GetResponseStream();
string json = string.Empty;
using (StreamReader reader = new StreamReader(stream))
{
while (!reader.EndOfStream)
{
json += reader.ReadLine();
}
}
JsonObject jsonObject = JsonObject.Parse(json);
_varStorage.Save("ObjectId", jsonObject.Get<string>("objectId"));
The bundleString value is:
"{\"channels\":\"\",\"deviceType\":\"ios\",\"deviceToken\":\"46becd0a165be042eeab5a1ec96b8858065cbea7311479da16c0fd1c9428e2eb\"}"
This code raises a System.Net.WebExceptionStatus.ProtocolError error 400 "Bad Request", and I can't see why.

Answer 1

Channels is supposed to be an array of strings according to the documentation, https://www.parse.com/docs/rest#installations
bundle.Add("channels", new [] { "" });

Answer 2

After more trail and error, I found that replacing this
byte[] buffer = Encoding.GetEncoding("UTF-8").GetBytes(bundleString);
string result = Convert.ToBase64String(buffer);
StreamWriter requestWriter = new StreamWriter(httpWebRequest.GetRequestStream());
requestWriter.Write(result, 0, result.Length);
requestWriter.Flush();
requestWriter.Close();
with this
httpWebRequest.ContentLength = bundleString.Length;
StreamWriter requestWriter = new StreamWriter(httpWebRequest.GetRequestStream());
requestWriter.Write(bundleString);
requestWriter.Flush();
requestWriter.Close();
fixed the problem, I don't know exactly why though.

Answer 3

should you not be calling flush before closing your stream ?
requestWriter.Write(result, 0, result.Length);
requestWriter.Close();