Add url parameter to status page with Formidable Forms

You would need to add some custom code to hook into the pronamic_payment_redirect_url_formidable-forms filter to use the success URL setting with field values as parameters from the Formidable Forms form setting. See sample code below.

/**
 * Redirect successful payment to Formidable Forms form success URL.
 *
 * @return string
 */
add_filter( 'pronamic_payment_redirect_url_formidable-forms', 'formidable_forms_payment_redirect_success_url', 10, 2 );

function formidable_forms_payment_redirect_success_url( $url, $payment ) {
	// Check if payment has been paid.
	if ( 'Success' !== $payment->get_status() ) {
		return $url;
	}

	// Get Formidable Forms entry and form.
	$entry_id = $payment->get_source_id();

	$entry = \FrmEntry::getOne( $entry_id );

	$form = \FrmForm::getOne( $entry->form_id );

	// Check if redirect success URL should be used.
	if ( 'redirect' === $form->options['success_action'] ) {
		$success_url = \trim( $form->options['success_url'] );

		$success_url = \apply_filters( 'frm_content', $success_url, $form, $entry_id );
	
		$success_url = \do_shortcode( $success_url );
	
		// Return success URL from settings.
		if ( ! empty( $success_url ) ) {
			return $success_url;
		}
	}

	// Return default URL.
	return $url;
}

Thank you for this, it works brilliantly!