mypmpro-save-utm-values.php

<?php //do not copy

/**
 * This recipe will save a utm_source value when a visitor lands on the checkout
 * page. This then gets stored in order meta upon successful checkout.
 * 
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function mypmpro_store_utm_checkout() {

	if ( ! empty( $_REQUEST['utm_source'] ) ) {
		//If utm_source is present in the URL, lets save it in session
		$_SESSION['pmpro_utm_source'] = sanitize_text_field( $_REQUEST['utm_source'] );
	}
	
}
add_action( 'pmpro_checkout_preheader', 'mypmpro_store_utm_checkout' );

function mypmpro_save_utm_to_order( $user_id, $morder ) {

	if( ! empty( $_SESSION['pmpro_utm_source'] ) ) {
		//If the session is available, lets save to order meta
		update_pmpro_membership_order_meta( $morder->id, 'utm_source', sanitize_text_field( $_SESSION['pmpro_utm_source'] ) );

		//Order is a success, remove the session
		if( $morder->status == 'success' ) {
			unset( $_SESSION['pmpro_utm_source'] );
		}
	}

}