How to get paypal smart payment button response to Flask

Question

I am trying to setup a Paypal payment in my Flask project. I am copying the smart payment button code from Paypal and pasted in my template. The payment process worked buy response details is in the javascript. How can I get the response back to my Flask app so that I can confirm the payment?

This is in my template:

<div id="paypal-button-container"></div>
    <script src="https://www.paypal.com/sdk/js?client-id=fake&currency=USD" data-sdk-integration-source="button-factory"></script>
    <script>
      paypal.Buttons({
          style: {
              shape: 'pill',
              color: 'gold',
              layout: 'vertical',
              label: 'paypal',
              
          },
          //method: 'POST',
          createOrder: function(data, actions) {
              return actions.order.create({
                  purchase_units: [{
                      amount: {
                          value: '10'
                      }
                  }]
              });
          },
          onApprove: function(data, actions) {
              return actions.order.capture().then(function(details) {
                    // Show a success message to the buyer
                   // window.write('Transaction completed by ' + details.payer.name.given_name + '!');
                  console.log("success");
                  return details;
              })
          }
              }).render('#paypal-button-container');

</script>

And app code:

@app.route('/upgrade/<username>', methods=['GET','POST'])
@login_required
def upgrade(username):
    user = User.query.filter_by(username=username).first()
    result = request.get_json()
    flash(result)
    return render_template('upgrade.html', user=user)  

Empty dict is returned by the flash message.

Answer 1

Flask is a server framework, so you should be using the following frontend UI: https://developer.paypal.com/demo/checkout/#/pattern/server

And paring it with two corresponding routes on your server, one for 'Set Up Transaction' and one for 'Capture Transaction', documented here: https://developer.paypal.com/docs/checkout/reference/server-integration/

You can use the Checkout-Python-SDK within those calls.