Connect to Presto Data in Google Apps Script via Connect AI

Google Apps Script empowers users to build custom functionality within their Google documents, including Google Sheets and Google Docs. Apps Script natively supports SQL Server connectivity via JDBC, providing a powerful extensibility tool for connecting Google cloud applications to external data. Paired with the SQL connectivity offered by CData Connect AI, users can easily access live Presto data directly from within their Google documents.

This article shows how to connect to Presto in Connect AI and provides sample scripting for processing Presto data in a Google Spreadsheet.

Getting Started

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Our script only reads data from a specified table, but you can easily extend the script to incorporate update functionality.

Configure Presto Connectivity for Google Apps Scripts

Connectivity to Presto from Google Apps Scripts is made possible through CData Connect AI. To work with Presto data from Google Apps Scripts, we start by creating and configuring a Presto connection.

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

1. Log into Connect AI, click Sources, and then click Add Connection
👁 Adding a Connection

2. Select "Presto" from the Add Connection panel
👁 Selecting a data source

3. Enter the necessary authentication properties to connect to Presto.

   Set the Server and Port connection properties to connect, in addition to any authentication properties that may be required.

   To enable TLS/SSL, set UseSSL to true.

   Authenticating with LDAP

   In order to authenticate with LDAP, set the following connection properties:

   • AuthScheme: Set this to LDAP.
   • User: The username being authenticated with in LDAP.
   • Password: The password associated with the User you are authenticating against LDAP with.

   Authenticating with Kerberos

   In order to authenticate with KERBEROS, set the following connection properties:

   • AuthScheme: Set this to KERBEROS.
   • KerberosKDC: The Kerberos Key Distribution Center (KDC) service used to authenticate the user.
   • KerberosRealm: The Kerberos Realm used to authenticate the user with.
   • KerberosSPN: The Service Principal Name for the Kerberos Domain Controller.
   • KerberosKeytabFile: The Keytab file containing your pairs of Kerberos principals and encrypted keys.
   • User: The user who is authenticating to Kerberos.
   • Password: The password used to authenticate to Kerberos.
   👁 Configuring a connection (Salesforce is shown)
   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add Presto Connection page and update the User-based permissions. 👁 Updating permissions
   

Add a Personal Access Token

When connecting to Connect AI through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect AI. It is best practice to create a separate PAT for each service to maintain granularity of access.

1. Click on the Gear icon () at the top right of the Connect AI app to open the settings page.
2. On the Settings page, go to the Access Tokens section and click Create PAT.
3. Give the PAT a name and click Create. 👁 Creating a new PAT
   
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to Presto data from Google Apps Script.

Connect to Presto Data from Apps Script

At this point, you should have configured a connection Presto in Connect AI. All that is left new is to use Google Apps Script to access Connect AI and work with your Presto 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 Presto data. We have created a sample script and explained the different parts. You can view the raw script at the and 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:

👁 Open script editor

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 = 'tds.cdata.com:14333';
var user = 'CONNECT_USER'; // [email protected]
var userPwd = 'CONNECT_USER_PAT';
var db = 'Presto1';

var dbUrl = 'jdbc:sqlserver://' + address + ';databaseName=' + db;

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: 'connectToPrestoData'}
 ];
 spreadsheet.addMenu('Presto Data', menuItems);
} 

👁 The newly added Menu option.

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 Presto Data to a Spreadsheet

The function below writes the Presto data, using the Google Apps Script JDBC functionality to connect to Connect AI, 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).

👁 Input box for sheet selection.

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

👁 Input box for table selection.

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 Presto 'table' and writes it to the specified sheet.
 * (If the specified sheet does not exist, it is created.)
 */
function connectToPrestoData() {
 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 Presto 'table'
 var table = Browser.inputBox('Which table would you like to pull data from?',Browser.Buttons.OK_CANCEL);
 if (table == 'cancel')
 return;

 var name = Jdbc.getConnection(dbUrl, {
 user: user, 
 password: userPwd
	}	
 );

 //confirm that var table is a valid table/view
 var dbMetaData = name.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 = name.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 Presto 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 Presto data, and you can now leverage all of the calculating, graphing, and charting functionality of Google Sheets anywhere you have access to the Internet.

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Complete Google Apps Script

//replace the variables in this block with real values as needed
var address = 'tds.cdata.com:14333';
var user = 'CONNECT_USER'; // [email protected]
var userPwd = 'CONNECT_USER_PAT';
var db = 'Presto1';

var dbUrl = 'jdbc:sqlserver://' + address + ';databaseName=' + db;

function onOpen() {
 var spreadsheet = SpreadsheetApp.getActive();
 var menuItems = [
 {name: 'Write table data to a sheet', functionName: 'connectToPrestoData'}
 ];
 spreadsheet.addMenu('Presto 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 connectToPrestoData() {
 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 Presto 'table'
 var table = Browser.inputBox('Which table would you like to pull data from?',Browser.Buttons.OK_CANCEL);
 if (table == 'cancel')
 return;

 var name = Jdbc.getConnection(dbUrl, {
 user: user, 
 password: userPwd
	}
 );

 //confirm that var table is a valid table/view
 var dbMetaData = name.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 = name.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 Presto 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();
}