Http Form Post

using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Collections.Specialized;

class DataService {
	public NameValueCollection Query { get; set; }
	public string Endpoint { get; set; }
	public FormUrlEncodedContent QueryEncoded {
		get {
			try {
				return new FormUrlEncodedContent( Query.AllKeys
					 .Select( s => new { Key = s, Value = Query[s] } )
					 .ToDictionary( p => p.Key, p => p.Value ) );
			} catch {
				return null;
			}
		}
	}

	public DataService() {
		Query = new NameValueCollection();
	}

	public void ClearQuery() {
		Query.Clear();
	}

	public async Task<string> Post() {
		ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
		string result = "";
		using( HttpClient client = new HttpClient() ) {
			HttpResponseMessage reply = await client.PostAsync( Endpoint, QueryEncoded );
			result = await reply.Content.ReadAsStringAsync();
		}
		return result;
	}

}