Open Event Frontend involves ticketing system which supports both paid and free tickets. To buy a paid ticket Open Event provides several options such as debit card, credit card, cheque, bank transfer and onsite payments. So to add support for debit and credit card payments Open Event uses Paypal checkout as one of the options. Using paypal checkout screen users can enter their card details and pay for their ticket or they can use their paypal wallet money to pay for their tickets.

Given below are some steps which are to be followed for successfully charging a user for ticket using his/her card.

• We create an application on paypal developer dashboard to receive client id and secret key.
• We set these keys in admin dashboard of open event and then while checkout we use these keys to render checkout screen.
• After clicking checkout button a request is sent to create-paypal-payment endpoint of open event server to create a paypal token which is used in checkout procedure.
• After user’s verification paypal generates a payment id is which is used by open event frontend to charge the user for stipulated amount.
• We send this token to open event server which processes the token and charge the user.
• We get error or success message from open event server as per the process outcome.

To render the paypal checkout elements we use paypal checkout library provided by npm. Paypal button is rendered using Button.render method of paypal checkout library. Code snippet is given below.

// app/components/paypal-button.js

paypal.Button.render({
   env: 'sandbox',

   commit: true,

   style: {
     label : 'pay',
     size  : 'medium', // tiny, small, medium
     color : 'gold', // orange, blue, silver
     shape : 'pill'    // pill, rect
   },

   payment() {
   // this is used to obtain paypal token to initialize payment process 
   },

   onAuthorize(data) {
     // this callback will be for authorizing the payments
    }

 }, this.elementId);

After button is rendered next step is to obtain a payment token from create-paypal-payment endpoint of open event server. For this we use the payment() callback of paypal-checkout. Code snippet for payment callback method is given below:

// app/components/paypal-button.js

let createPayload = {
      'data': {
        'attributes': {
          'return-url' : `${window.location.origin}/orders/${order.identifier}/placed`,
          'cancel-url' : `${window.location.origin}/orders/${order.identifier}/placed`
        },
        'type': 'paypal-payment'
      }
    };
paypal.Button.render({
     //Button attributes

      payment() {
        return loader.post(`orders/${order.identifier}/create-paypal-payment`, createPayload)
          .then(res => {
            return res.payment_id;
          });
      },

      onAuthorize(data) {
        // this callback will be for authorizing the payments
      }

    }, this.elementId);

After getting the token payment screen is initialized and user is asked to enter his/her credentials. This process is handled by paypal servers. After user verifies his/her payment paypal generates a paymentId and a payerId and sends it back to open event. After the payment authorization onAuthorize() method of paypal is called and payment is further processed in this callback method. Payment ID and payer Id received from paypal is sent to charge endpoint of open event server to charge the user. After receiving success or failure message from paypal proper message is displayed to users and their order is confirmed or cancelled respectively. Code snippet for onAuthorize is given below:

// app/components/paypal-button.js

onAuthorize(data) {
        // this callback will be for authorizing the payments
        let chargePayload = {
          'data': {
            'attributes': {
              'stripe'            : null,
              'paypal_payer_id'   : data.payerID,
              'paypal_payment_id' : data.paymentID
            },
            'type': 'charge'
          }
        };
        let config = {
          skipDataTransform: true
        };
        chargePayload = JSON.stringify(chargePayload);
        return loader.post(`orders/${order.identifier}/charge`, chargePayload, config)
          .then(charge => {
            if (charge.data.attributes.status) {
              notify.success(charge.data.attributes.message);
              router.transitionTo('orders.view', order.identifier);
            } else {
              notify.error(charge.data.attributes.message);
            }
          });
      }

Full code can be seen here.

In this way we achieve the functionality of adding paypal payment support in open event frontend. Please follow the links below for further clarification and detailed overview.

Resources:

• Link to PR: Part 1, Part 2
• Charge endpoint: open event server: https://open-event-api-dev.herokuapp.com/#orders-charge-post
• Paypal checkout docs: https://developer.paypal.com/docs/checkout/how-to/server-integration/