ElasticSearch-Use elasticsearch.net create attachment type of document

gistfile1.cs

            //oepn file and convert to base64
            FileStream inFile = System.IO.File.Open(@"c:\\testtest.docx", FileMode.OpenOrCreate, FileAccess.Read);
            byte[] binaryData = new Byte[inFile.Length];
            inFile.Read(binaryData, 0, (int)inFile.Length);
            inFile.Close();
            var base64String = System.Convert.ToBase64String(binaryData, 0, binaryData.Length);
            //----------------------------------------------------------------------
            
            //create elasticsearch connect
            var client = new ElasticsearchClient();           
            var myJson = new
            {
                file = base64String
            };
            
            //(Index,Type,Id,document)
            client.Index("test", "attachment", "1", myJson);