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PayPal Payment Integration

This document describes the PayPal payment functionality implemented for NOW LMS.

Overview

The PayPal integration allows students to pay for courses using PayPal's secure payment processing. The system supports:

  • Free courses: Immediate enrollment
  • Paid courses: Payment required via PayPal before enrollment
  • Audit mode: Free access to course content without certificates (for auditable courses)

Features

Course Enrollment Flow

  1. Free Courses: Students can enroll immediately without payment
  2. Paid Courses:
  3. Creates a pending payment record
  4. Redirects to PayPal for secure payment
  5. Creates course enrollment only after successful payment
  6. Audit Mode: Students can access course content without payment but cannot receive certificates

Payment Processing

  • Uses PayPal REST API SDK for secure payment processing
  • Supports both sandbox (development) and live (production) environments
  • Encrypted storage of PayPal API credentials
  • Automatic payment status updates based on PayPal responses

Security

  • PayPal API credentials are encrypted before storage
  • Secure redirect to PayPal's payment pages
  • Payment verification through PayPal's API
  • CSRF protection on all forms

Configuration

PayPal Developer Setup

  1. Create a PayPal Developer account at https://developer.paypal.com
  2. Create a new application for your LMS
  3. Note down your Client ID and Client Secret for both sandbox and live environments

LMS Configuration

  1. Go to Admin Panel → Settings → PayPal Configuration
  2. Enable PayPal payments
  3. Configure your PayPal credentials:
  4. Sandbox Mode: Use for testing and development
  5. Production Mode: Use for live payments

Configuration Fields

  • Enable PayPal: Toggle to enable/disable PayPal payments
  • Sandbox Mode: Toggle between sandbox and production
  • Client ID (Production): Your live PayPal Client ID
  • Client Secret (Production): Your live PayPal Client Secret
  • Client ID (Sandbox): Your sandbox PayPal Client ID
  • Client Secret (Sandbox): Your sandbox PayPal Client Secret

PayPal Return URLs

Configure these URLs in your PayPal application:

  • Return URL: https://yourdomain.com/paypal_checkout/execute_payment/{payment_id}
  • Cancel URL: https://yourdomain.com/paypal_checkout/cancel_payment/{payment_id}

Database Schema

New Fields in PaypalConfig

  • paypal_secret: Encrypted production client secret
  • paypal_sandbox_secret: Encrypted sandbox client secret

Payment Records (Pago)

Payment records track the following states: - pending: Payment created, awaiting PayPal processing - completed: Payment successful, course enrollment created - failed: Payment failed or cancelled

API Endpoints

Payment Processing Routes

  • POST /course/{course_code}/enroll - Course enrollment with payment logic
  • GET /paypal_checkout/create_payment/{payment_id} - Create PayPal payment
  • GET /paypal_checkout/execute_payment/{payment_id} - Handle successful payment
  • GET /paypal_checkout/cancel_payment/{payment_id} - Handle cancelled payment

Error Handling

The system handles various error scenarios:

  • PayPal API configuration errors
  • Payment creation failures
  • Payment execution failures
  • Network connectivity issues
  • Invalid payment states

Users receive appropriate error messages and are redirected to safe pages.

Testing

Unit Tests

Run the payment flow tests:

python -m pytest tests/test_payment_flow.py -v

Manual Testing

  1. Create a test course with payment enabled
  2. Attempt enrollment as a student
  3. Verify redirect to PayPal sandbox
  4. Complete or cancel payment
  5. Verify correct enrollment status

Test Scenarios

  • Free course enrollment
  • Paid course enrollment with successful payment
  • Paid course enrollment with cancelled payment
  • Audit mode enrollment
  • PayPal configuration errors

Security Considerations

  • All PayPal API credentials are encrypted in the database
  • Payment amounts are validated against course prices
  • User authentication is required for all payment operations
  • CSRF tokens protect against cross-site request forgery
  • Payment status is verified through PayPal API

Troubleshooting

Common Issues

  1. PayPal credentials not configured
  2. Ensure Client ID and Secret are set in admin panel

  3. Verify credentials are correct for your environment (sandbox/live)

  4. Payment creation fails

  5. Check PayPal API connectivity
  6. Verify return URLs are configured correctly

  7. Check application logs for API errors

  8. Students not enrolled after payment

  9. Verify payment execution callback is working
  10. Check payment status in database
  11. Ensure course enrollment logic is not failing

Logging

Payment operations are logged for debugging: - Payment creation attempts - PayPal API responses - Payment status changes - Error conditions

Maintenance

Regular Tasks

  • Monitor payment success rates
  • Review failed payment logs
  • Update PayPal credentials as needed
  • Test payment flow periodically

Updates

When updating PayPal integration: - Test in sandbox environment first - Verify backward compatibility - Update documentation as needed - Communicate changes to administrators