public string ConvertDateTimeToJsonStr(DateTime date)
        {
            try
            {
                //var bsonDocument = new BsonDocument();
                var assembly = new StiDataAssemblyHelper("MongoDB.Bson.dll");

                //var bsonElement = new BsonElement("date", BsonValue.Create(date));
                var bsonValue   = assembly.GetType("MongoDB.Bson.BsonValue").GetMethod("Create").Invoke(null, new object[] { date });
                var bsonElement = assembly.CreateObject("MongoDB.Bson.BsonElement", "date", bsonValue);

                var str = bsonElement.ToString().Replace("date=", "");

                return(string.Format("\"{0}\"", str));
            }
            catch
            {
                return(null);
            }
        }
        private string GetAsJson(object obj)
        {
            var assembly = new StiDataAssemblyHelper("MongoDB.Bson.dll");

            var settings = assembly.CreateObject("MongoDB.Bson.IO.JsonWriterSettings");

            settings.GetType().GetProperty("OutputMode").SetValue(settings, 0, null);

            using (var writer = new StringWriter())
            {
                //var writer2 = BsonWriter.Create(writer, settings as JsonWriterSettings);
                var method = assembly.GetType("MongoDB.Bson.IO.BsonWriter").GetMethod("Create", new[] { writer.GetType(), settings.GetType() });
                using (var writer2 = method.Invoke(null, new[] { writer, settings }) as IDisposable)
                {
                    var bsonWriterType = assembly.GetType("MongoDB.Bson.IO.BsonWriter");
                    //BsonSerializer.Serialize(writer2, typeof(object), obj);
                    method = assembly.GetType("MongoDB.Bson.Serialization.BsonSerializer").GetMethod("Serialize", new[] { bsonWriterType, typeof(Type), obj.GetType() });
                    method.Invoke(null, new[] { writer2, typeof(object), obj });

                    return(writer.ToString());
                }
            }
        }