100 Days of Cloud: Day 10 – Building a Paystack Webhook with Google Apps Script

Welcome to Day 10 of our 100 Days of Cloud series! Today, we're focusing on a powerful integration technique using Google Apps Script. Instead of just fetching data and updating a Google Sheet on a schedule, we’ll be turning our script into a web app that acts as a webhook. This will allow Paystack to push data to our Google Sheet in real-time whenever a payment event occurs.

What is a Webhook?

A webhook is a way for an application to provide other applications with real-time information. It’s a lightweight, event-driven approach to integrating different services. In our case, Paystack can send payment data directly to our Google Apps Script web app, which will then write this data into a Google Sheet automatically.

Setting Up Your Environment

Before diving into the code, ensure you have:

1. Google Account: Needed for Google Sheets and Google Apps Script.
2. Paystack Account: For API access and setting up webhooks.
3. Google Sheet: Where the Paystack data will be recorded.

Step 1: Create and Prepare Your Google Sheet

1. Open Google Sheets and create a new spreadsheet. Name it "Paystack Payments Data" or something similar.
2. Set up the columns you want to track. For example:
   • Transaction ID
   • Email
   • Amount
   • Date
   • Status

Step 2: Open Google Apps Script

1. In your Google Sheet, go to Extensions > Apps Script.
2. This opens the Google Apps Script editor. Clear any existing code and prepare to add your webhook script.

Step 3: Write the Webhook Script

Replace any existing code in the Apps Script editor with the following:

// Webhook function to handle incoming requests from Paystack
function doPost(e) {
  try {
    // Parse the JSON payload sent by Paystack
    const jsonPayload = JSON.parse(e.postData.contents);

    // Extract transaction data
    const transaction = jsonPayload.data;

    // Get the active sheet
    const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();

    // Append data to the sheet
    sheet.appendRow([
      transaction.id,
      transaction.email,
      transaction.amount,
      new Date(transaction.created_at),
      transaction.status
    ]);

    // Return a success response to Paystack
    return ContentService.createTextOutput('Success');
  } catch (error) {
    // Log error and return error response
    Logger.log(error.toString());
    return ContentService.createTextOutput('Error');
  }
}

Explanation of the Code

• doPost(e): This is the main function that handles POST requests. It’s automatically invoked when your web app receives data.
  • Parsing the Payload: The JSON payload sent by Paystack is parsed.
  • Extracting Data: Transaction details are extracted from the payload.
  • Writing to Sheet: The data is appended to the active Google Sheet.
  • Error Handling: Logs errors and returns a simple success or error message.

Step 4: Deploy the Script as a Web App

1. Click on Deploy > New deployment in the Apps Script editor.
2. Choose Web app as the deployment type.
3. Configure the deployment settings:
   • Description: Provide a description for your deployment.
   • Execute as: Choose “Me” to ensure the script runs with your permissions.
   • Who has access: Select “Anyone” or “Anyone with Google account” based on your security needs.
4. Click Deploy and authorize the app to access your Google Sheet.
5. Copy the web app URL provided after deployment. This URL will be used as the webhook endpoint.

Step 5: Set Up Paystack Webhook

1. Log in to your Paystack dashboard.
2. Navigate to Settings > Webhooks.
3. Click on + Add New Webhook.
4. Enter the web app URL you obtained from the Google Apps Script deployment.
5. Choose the events you want to receive. For instance, select successful payments or other relevant events.
6. Save the webhook configuration.

Step 6: Testing the Webhook

1. Trigger a Test Event: Perform a test transaction in Paystack or use the “Test Webhook” feature in the Paystack dashboard to send a test payload to your webhook URL.
2. Check Your Google Sheet: Verify that the test data appears in your Google Sheet.

Troubleshooting

• Permission Issues: Ensure that the script has permission to access and modify your Google Sheet.
• Data Format: If the data isn’t being written correctly, check the format of the JSON payload from Paystack and adjust the parsing logic if necessary.
• Deployment Errors: Double-check deployment settings and URL. Make sure your web app is accessible and correctly set up.

Conclusion

You’ve successfully set up a Google Apps Script webhook to handle Paystack payment events and update a Google Sheet in real-time. This integration will help streamline your payment tracking and ensure your data is always up-to-date.

Stay tuned for more cloud automation tips and tricks in our 100 Days of Cloud series. If you have any questions or run into issues, feel free to leave a comment below!

Happy automating! 🚀