Update field in Gravity Forms entry with IBAN on successful payment with Pronamic Pay.

functions.php

<?php

/**
 * Gravity Forms - Update field in entry with IBAN / account number from Pronamic Pay payment.
 *
 * @link https://github.com/pronamic/wp-pronamic-pay-gravityforms/blob/2200b1e0d275f3207326e3fcbb925a5c2b16bc1d/src/Extension.php#L1057-L1067
 *
 * @param array                                                   $entry Gravity Forms entry.
 * @param \Pronamic\WordPress\Pay\Extensions\GravityForms\PayFeed $feed  Payment feed.
 */
function gform_ideal_fulfillment_update_entry( $entry, $feed ) {
	// Set form and field ID you want to update with IBAN / account number.
	$form_id    = 2;
	$field_id   = 26;

	// Check if we want to update for this form.
	if ( $form_id !== (int) $entry['form_id'] ) {
		return;
	}

	// Get Pronamic payment.
	$payment_id = gform_get_meta( $entry['id'], 'pronamic_payment_id' );

	$payment = get_pronamic_payment( $payment_id );

	if ( null === $payment ) {
		return;
	}

	$consumer_bank_details = $payment->get_consumer_bank_details();

	if ( null === $consumer_bank_details ) {
		return;
	}

	// Use account number...
	$consumer_account = $consumer_bank_details->get_account_number();

	if ( ! empty( $consumer_account ) ) {
		$entry[ $field_id ] = $consumer_account;
	}

	// ...or IBAN.
	$consumer_iban = $consumer_bank_details->get_iban();

	if ( ! empty( $consumer_iban ) ) {
		$entry[ $field_id ] = $consumer_iban;
	}

	GFAPI::update_entry( $entry );
}

add_action( 'gform_ideal_fulfillment', 'gform_ideal_fulfillment_update_entry', 10, 2 );