Perch Shop - Braintree - Generating Client Token

Hi guys,

I'm having some issues generating a Client Token for use with the Drop-in Payment UI.

• Is anybody able to provide some code examples of how we're supposed to do this? I've been going round in circles in the Braintree docs!
• Do we need to generate a fresh Client Token for each visitor?

I've got this so far:

checkout.php:

<?php

perch_shop_cart([
    'template'=>'cart/cart_static.html'
]);

perch_shop_order_addresses();


perch_shop_payment_form('braintree');

if (perch_member_logged_in() && perch_post('payment_method_nonce')) {

$return_url = 'https://staging.flykartel.com/shop/success';

perch_shop_checkout('braintree', [
    'return_url' => $return_url,
    'cancel_url' => 'https://staging.flykartel.com',
    'token'      => perch_post('payment_method_nonce')
]);
}

?>

braintree_payment_form.html (just the ajax call):

var clientToken = 
$.ajax({
    type: "GET",
    url: "/cms/templates/pages/shop/gen_client_token.php",
    success: function(){
        console.log('Y')
    },
    error: function(){
        console.log('N')
    }
});

braintree.setup(clientToken, "dropin", {
  container: 'dropin-container',
  paypal: {
    singleUse: true,
    amount: <perch:shop id="amount" escape="true" />,
    currency: '<perch:shop id="currency" escape="true" />'
  },
});

gen_client_token.php:

<?php echo($clientToken = Braintree_ClientToken::generate()); ?>

The trouble is that the AJAX call just returns an error about the Braintree_Configuration class not being found, or about how the merchantID has to be set.

Everything's already set up, and the payment gateway does actually work, I managed to generate a client token by echoing it out, copying it and pasting it in to the braintree.setup call, but if we have to generate a new token for each client, that's obviously not going to work.

Any ideas?

Thanks! Harry