Use REDIRECT_GET on CheckoutForm

Tried to figure out from the official documentation whether Postfinance actually specifies whether the request needs to be GET or POST. Reviewed the following documents:

• Payment Page section in the Integration Modes chapter. (not specified)
• API docs on the TransactionPaymentPageService::paymentPageUrl() method. That one has an interesting example (click on the PHP tab:
  

  [...]
  $transaction    = $transactionService->create($spaceId, $transactionPayload);
  $paymentPageUrl = $transactionPaymentPageService->paymentPageUrl($spaceId, $transaction->getId());
  
  header('Location: '. $paymentPageUrl);
  

• The same piece of code is also in the README.md on the PHP SDK project.

So, yes. IMHO the POST step is superflous and should be removed.

Switched to MR workflow and updated checkout form test.

Took this out for a manual test drive with the setup documented in the account setup guide → .

The GET redirect works well and reduces the time from the review checkout pane to the payment form considerably.

Automatically closed - issue fixed for 2 weeks with no activity.