Paypal Checkout not working without "Review" pane active

It looks like the remote_Id we get from PayPal wasn't stored in the payment method remote_id field... Maybe something wrong happened when creating/approving the order?

Could you try to debug CheckoutController::onCreate or CheckoutController::onApprove? See if it enters there... And also check if you have other info in the logs?

The proposed improvements sound good, feel free to send patches / edit the documentation page (I'd be more than happy to review).

The reason why the Smart payment buttons are shown on the review page is that it's hard to show them directly from the PaymentInformation pane for various reasons:

1. If PayPal Checkout is the only option available, the option isn't even shown in Checkout (See #2907504: Display payment method in the CheckoutPane Payment informations even if only single payment gateway available).
2. It'd be confusing in terms of UX to show payment logos below the radio buttons.
3. The checkout panes at this point are not yet validated/saved meaning the shipping/promotions might not be applied yet (Which means we wouldn't send the correct data to PayPal.

Or... make PayPal Checkout usable without the review pane.

It is usable... It just needs some custom code, if you need to adapt it to your custom flow.

The only thing you'd have to do is something like the following:

    $form['paypal_smart_payment_buttons'] = [
      '#type' => 'commerce_paypal_smart_payment_buttons',
      '#commit' => FALSE,
      '#order' => $order,
      '#payment_gateway' => $payment_gateway,
      '#weight' => 100,
    ];

FYI we have a documentation page that needs to be updated to describe the 2 different flows (i.e the "shortcut" flow where you initiate the payment from the cart page, and the "mark" flow, when PayPal is being used just like another regular payment gateway).

See https://www.drupal.org/node/3042053.

If we define the buttons in an offsite-form as well, then anyone without a Review step would still get the PayPal buttons on the separate Payment step. It's bad UX, and I don't know why anyone would do it (VS just having a Review step), but it's better than nothing.

As per #10, I can't seem to get the "Mark flow" working. No issues with the "Shortcut flow" though.

Maybe someone can elaborate a bit more on what is needed for the "Mark flow" to work properly. I've made sure to make use of the Review step.

I'm also thinking that the "Shortcut flow" is an interesting idea. It seems to work well, but I'm finding it a little confusing that the user has two options. I wonder if we could just offer the user with one option: the "Shortcut flow" if desired by a site builder?

As suggested by Bojan in #12, we actually already provide an offsite form in the event no "review" step is present, so I believe this issue is now outdated.

I'm having the same issue with a checkout process that involves only 'order_information' and 'payment' steps, but no review step. The information in #12 does not appear to be correct. I simply see an error and no offsite form. The error is a `commerce_payment` error of:

Cannot create the payment without the PayPal order ID.

To clarify #9 as a solution is not entirely accurate and may simply be out of date. I'm using this in a form_alter successfully.

$cart_provider = \Drupal::service('commerce_cart.cart_provider');
$carts = $cart_provider->getCarts();
if($carts) {
$order = array_shift($carts); // This works if you assume one cart
$payment_gateway_storage = \Drupal::service('entity_type.manager')->getStorage('commerce_payment_gateway');
$paypal_payment_gateway = $payment_gateway_storage->load('machine_name_of_your_paypal_gateway');
$builder = \Drupal::service('commerce_paypal.smart_payment_buttons_builder');
$form["payment_information"]['paypal_smart_payment_buttons'] = $builder->build($order, $paypal_payment_gateway, FALSE);
}

I don't think this is outdated. PayPal Checkout does not seems to work without review step in the default configuration.

Cannot create the payment without the PayPal order ID.

@brooke_heaton Can you please elaborate, which form you are altering in the mentioned form_alter? Thanks!

Edit: Just to be sure, I mean the "mark" flow, not the payment buttons (shortcut). It is a bit unfortunate, that this is not working, because Express checkout is deprecated and therefore there is no working offsite option in 8.x version of this modules without the review step. But I will understand if this is "won't fix".