How to connect to Google Cloud Storage Data from Google Apps Script

Google Apps Script gives you the ability to create custom functionality within your Google documents, including Google Sheets, Google Docs, and more. With CData Connect Server, you get a SQL Server interface for any of the 200+ sources supported by CData, including Google Cloud Storage. The SQL Server protocol is natively supported through the JDBC service in Google Apps Script, so by utilizing Connect Server, you gain access to live Google Cloud Storage data within your Google documents.

This article shows how to create a virtual database for Google Cloud Storage in Connect Server and provides sample scripting for processing Google Cloud Storage data in a Google Spreadsheet.

CData Connect Server provides a pure SQL Server interface for Google Cloud Storage, allowing you to easily build reports from live Google Cloud Storage data in Apps Script — without replicating the data to a natively supported database. As you build visualizations, Apps Script generates SQL queries to gather data. Using optimized data processing out of the box, CData Connect Server pushes all supported SQL operations (filters, JOINs, etc) directly to Google Cloud Storage, leveraging server-side processing to quickly return the requested Google Cloud Storage data.

Create a Virtual SQL Server Database for Google Cloud Storage Data

CData Connect Server uses a straightforward, point-and-click interface to connect to data sources and generate APIs.

1. Login to Connect Server and click Connections.
2. Select "Google Cloud Storage" from Available Data Sources.
3. Enter the necessary authentication properties to connect to Google Cloud Storage.

   Authenticate with a User Account

   You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

   When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

   Authenticate with a Service Account

   Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

   You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

   • InitiateOAuth: Set this to GETANDREFRESH.
   • OAuthJWTCertType: Set this to "PFXFILE".
   • OAuthJWTCert: Set this to the path to the .p12 file you generated.
   • OAuthJWTCertPassword: Set this to the password of the .p12 file.
   • OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
   • OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
   • OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
   • ProjectId: Set this to the Id of the project you want to connect to.

   The OAuth flow for a service account then completes.

4. Click Save Changes
5. Click Privileges -> Add and add the new user (or an existing user) with the appropriate permissions.

With the virtual database created, you are ready to connect to Google Cloud Storage data from Apps Script.

Connect to Google Cloud Storage Data with Apps Script

At this point, you should have configured a virtual database for Google Cloud Storage in Connect Server. All that is left now is to use Google Apps Script to access Connect Server and work with your Google Cloud Storage data in Google Sheets.

In this section, you will create a script (with a menu option to call the script) to populate a spreadsheet with Google Cloud Storage data. We have created a sample script and explained the different parts. You can view the raw script at the end of the article.

1. Create an Empty Script

To create a script for your Google Sheet, click Tools Script editor from the Google Sheets menu:

2. Declare Class Variables

Create a handful of class variables to be available for any functions created in the script.

//replace the variables in this block with real values as needed
var address = 'CONNECT_SERVER_URL:port';
var user = 'CONNECT_USER';
var userPwd = 'CONNECT_PASSWORD';
var db = 'googlecloudstoragedb';
var serverSslCert = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';
var clientSslCert = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';
var clientSslKey  = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';

var dbUrl = 'jdbc:sqlserver://' + address + '/' + db + '?useSSL=true';

3. Add a Menu Option

This function adds a menu option to your Google Sheet, allowing you to use the UI to call your function.

function onOpen() {
  var spreadsheet = SpreadsheetApp.getActive();
  var menuItems = [
    {name: 'Write data to a sheet', functionName: 'connectToGoogleCloudStorageData'}
  ];
  spreadsheet.addMenu('Google Cloud Storage Data', menuItems);
} 

4. Write a Helper Function

This function is used to find the first empty row in a spreadsheet.

/*
 * Finds the first empty row in a spreadsheet by scanning an array of columns
 * @return The row number of the first empty row.
 */
function getFirstEmptyRowByColumnArray(spreadSheet, column) {
  var column = spreadSheet.getRange(column + ":" + column);
  var values = column.getValues(); // get all data in one call
  var ct = 0;
  while ( values[ct] && values[ct][0] != "" ) {
    ct++;
  }
  return (ct+1);
}

5. Write a Function to Write Google Cloud Storage Data to a Spreadsheet

The function below writes the Google Cloud Storage data, using the Google Apps Script JDBC functionality to connect to Connect Server, SELECT data, and populate a spreadsheet. When the script is run, two input boxes will appear:

The first one asks the user to input the name of a sheet to hold the data (if the spreadsheet does not exist, the function creates it).

The second asks the user to input the name of a Google Cloud Storage table to read. If an invalid table is chosen, an error message appears and the function is exited.

Note, while the function is designed for use as a menu option, you can extend it for use as a spreadsheet formula.

/*
 * Reads data from a specified Google Cloud Storage 'table' and writes it to the specified sheet.
 *    (If the specified sheet does not exist, it is created.)
 */
function connectToGoogleCloudStorageData() {
  var thisWorkbook = SpreadsheetApp.getActive();

  //select a sheet and create it if it does not exist
  var selectedSheet = Browser.inputBox('Which sheet would you like the data to post to?',Browser.Buttons.OK_CANCEL);
  if (selectedSheet == 'cancel')
    return;

  if (thisWorkbook.getSheetByName(selectedSheet) == null)
    thisWorkbook.insertSheet(selectedSheet);
  var resultSheet = thisWorkbook.getSheetByName(selectedSheet);
  var rowNum = 2;

  //select a Google Cloud Storage 'table'
  var table = Browser.inputBox('Which table would you like to pull data from?',Browser.Buttons.OK_CANCEL);
  if (table == 'cancel')
    return;

  var conn = Jdbc.getConnection(dbUrl, {
    user: user, 
    password: userPwd, 
    _serverSslCertificate: serverSslCert,
    _clientSslCertificate: clientSslCert,
    _clientSslKey:         clientSslKey
  );

  //confirm that var table is a valid table/view
  var dbMetaData = conn.getMetaData();
  var tableSet = dbMetaData.getTables(null, null, table, null);
  var validTable = false;
  while (tableSet.next()) {
    var tempTable = tableSet.getString(3);
    if (table.toUpperCase() == tempTable.toUpperCase()){
      table = tempTable;
      validTable = true;
      break;
    }
  } 
  tableSet.close();
  if (!validTable) {
    Browser.msgBox("Invalid table name: " + table, Browser.Buttons.OK);
    return;
  }

  var stmt = conn.createStatement();

  var results = stmt.executeQuery('SELECT * FROM ' + table);
  var rsmd = results.getMetaData();
  var numCols = rsmd.getColumnCount();

  //if the sheet is empty, populate the first row with the headers
  var firstEmptyRow = getFirstEmptyRowByColumnArray(resultSheet, "A");
  if (firstEmptyRow == 1) {
    //collect column names
    var headers = new Array(new Array(numCols));
    for (var col = 0; col < numCols; col++){
      headers[0][col] = rsmd.getColumnName(col+1);
    }
    resultSheet.getRange(1, 1, headers.length, headers[0].length).setValues(headers);
  } else {
    rowNum = firstEmptyRow;
  }

  //write rows of Google Cloud Storage data to the sheet
  var values = new Array(new Array(numCols));
  while (results.next()) {
    for (var col = 0; col < numCols; col++) {
      values[0][col] = results.getString(col + 1);
    }
    resultSheet.getRange(rowNum, 1, 1, numCols).setValues(values);
    rowNum++;
  }

  results.close();
  stmt.close();
}
  

When the function is completed, you have a spreadsheet populated with your Google Cloud Storage data, and you can now leverage all of the calculating, graphing, and charting functionality of Google Sheets anywhere you have access to the Internet.

Complete Google Apps Script

//replace the variables in this block with real values as needed
var address = 'CONNECT_SERVER_URL:port';
var user = 'CONNECT_USER';
var userPwd = 'CONNECT_PASSWORD';
var db = 'googlecloudstoragedb';
var serverSslCert = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';
var clientSslCert = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';
var clientSslKey  = '-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----';

var dbUrl = 'jdbc:sqlserver://' + address + '/' + db + '?useSSL=true';

function onOpen() {
  var spreadsheet = SpreadsheetApp.getActive();
  var menuItems = [
    {name: 'Write table data to a sheet', functionName: 'connectToGoogleCloudStorageData'}
  ];
  spreadsheet.addMenu('Google Cloud Storage Data', menuItems);
}

/*
 * Finds the first empty row in a spreadsheet by scanning an array of columns
 * @return The row number of the first empty row.
 */
function getFirstEmptyRowByColumnArray(spreadSheet, column) {
  var column = spreadSheet.getRange(column + ":" + column);
  var values = column.getValues(); // get all data in one call
  var ct = 0;
  while ( values[ct] && values[ct][0] != "" ) {
    ct++;
  }
  return (ct+1);
}

/*
 * Reads data from a specified 'table' and writes it to the specified sheet.
 *    (If the specified sheet does not exist, it is created.)
 */
function connectToGoogleCloudStorageData() {
  var thisWorkbook = SpreadsheetApp.getActive();

  //select a sheet and create it if it does not exist
  var selectedSheet = Browser.inputBox('Which sheet would you like the data to post to?',Browser.Buttons.OK_CANCEL);
  if (selectedSheet == 'cancel')
    return;

  if (thisWorkbook.getSheetByName(selectedSheet) == null)
    thisWorkbook.insertSheet(selectedSheet);
  var resultSheet = thisWorkbook.getSheetByName(selectedSheet);
  var rowNum = 2;

  //select a Google Cloud Storage 'table'
  var table = Browser.inputBox('Which table would you like to pull data from?',Browser.Buttons.OK_CANCEL);
  if (table == 'cancel')
    return;

  var conn = Jdbc.getConnection(dbUrl, {
    user: user, 
    password: userPwd, 
    _serverSslCertificate: serverSslCert,
    _clientSslCertificate: clientSslCert,
    _clientSslKey:         clientSslKey
  );

  //confirm that var table is a valid table/view
  var dbMetaData = conn.getMetaData();
  var tableSet = dbMetaData.getTables(null, null, table, null);
  var validTable = false;
  while (tableSet.next()) {
    var tempTable = tableSet.getString(3);
    if (table.toUpperCase() == tempTable.toUpperCase()){
      table = tempTable;
      validTable = true;
      break;
    }
  } 
  tableSet.close();
  if (!validTable) {
    Browser.msgBox("Invalid table name: " + table, Browser.Buttons.OK);
    return;
  }

  var stmt = conn.createStatement();

  var results = stmt.executeQuery('SELECT * FROM ' + table);
  var rsmd = results.getMetaData();
  var numCols = rsmd.getColumnCount();

  //if the sheet is empty, populate the first row with the headers
  var firstEmptyRow = getFirstEmptyRowByColumnArray(resultSheet, "A");
  if (firstEmptyRow == 1) {
    //collect column names
    var headers = new Array(new Array(numCols));
    for (var col = 0; col < numCols; col++){
      headers[0][col] = rsmd.getColumnName(col+1);
    }
    resultSheet.getRange(1, 1, headers.length, headers[0].length).setValues(headers);
  } else {
    rowNum = firstEmptyRow;
  }

  //write rows of Google Cloud Storage data to the sheet
  var values = new Array(new Array(numCols));
  while (results.next()) {
    for (var col = 0; col < numCols; col++) {
      values[0][col] = results.getString(col + 1);
    }
    resultSheet.getRange(rowNum, 1, 1, numCols).setValues(values);
    rowNum++;
  }

  results.close();
  stmt.close();
}