Google Sheets API and Service Account

gistfile1.txt

 public class SpreadSheetConnector {

    private string[] _scopes = { SheetsService.Scope.Spreadsheets }; // Change this if you're accessing Drive or Docs
    private string _applicationName = "My Application Name from Google API Project ";
    private string _spreadsheetId = "xdMsqBc3wblahblahblahblahkeygoeshere";
    private SheetsService _sheetsService;

    private void ConnectToGoogle() {
        GoogleCredential credential;

        // Put your credentials json file in the root of the solution and make sure copy to output dir property is set to always copy 
        using (var stream = new FileStream(Path.Combine(HttpRuntime.BinDirectory, "credentials.json"), 
            FileMode.Open, FileAccess.Read)) {
                credential = GoogleCredential.FromStream(stream).CreateScoped(_scopes);
        }

        // Create Google Sheets API service.
        _sheetsService = new SheetsService(new BaseClientService.Initializer() { 
            HttpClientInitializer = credential, ApplicationName = _applicationName 
        });
    }

    // Pass in your data as a list of a list (2-D lists are equivalent to the 2-D spreadsheet structure)
    public string UpdateData(List<IList<object>> data) { 
        String range = "My Tab Name!A1:Y";
        string valueInputOption = "USER_ENTERED";

        // The new values to apply to the spreadsheet.
        List<Data.ValueRange> updateData = new List<Data.ValueRange>();
        var dataValueRange = new Data.ValueRange();
        dataValueRange.Range = range;
        dataValueRange.Values = data;
        updateData.Add(dataValueRange);

        Data.BatchUpdateValuesRequest requestBody = new Data.BatchUpdateValuesRequest();
        requestBody.ValueInputOption = valueInputOption;
        requestBody.Data = updateData;

        var request = _sheetsService.Spreadsheets.Values.BatchUpdate(requestBody, _spreadsheetId);

        Data.BatchUpdateValuesResponse response = request.Execute();
        // Data.BatchUpdateValuesResponse response = await request.ExecuteAsync(); // For async 

        return JsonConvert.SerializeObject(response);
    }
}