Reworking how pixel events on redirect to cart are handled.

facebook-commerce-events-tracker.php

@@ -116,9 +116,8 @@ private function add_hooks() {
 			add_action( 'woocommerce_ajax_added_to_cart', array( $this, 'add_filter_for_add_to_cart_fragments' ) );
 			// AddToCart while using redirect to cart page
 			if ( 'yes' === get_option( 'woocommerce_cart_redirect_after_add', 'no' ) ) {
-				add_filter( 'woocommerce_add_to_cart_redirect', array( $this, 'set_last_product_added_to_cart_upon_redirect' ), 10, 2 );
-				add_action( 'woocommerce_ajax_added_to_cart', array( $this, 'set_last_product_added_to_cart_upon_ajax_redirect' ) );
-				add_action( 'woocommerce_after_cart', array( $this, 'inject_add_to_cart_redirect_event' ), 10, 2 );
+				add_action( 'wp_head', array( WC_Facebookcommerce_Utils::class, 'print_deferred_events' ) );
+				add_action( 'shutdown', array( WC_Facebookcommerce_Utils::class, 'save_deferred_events' ) );
 			}
 
 			// InitiateCheckout events
@@ -563,8 +562,8 @@ public function inject_add_to_cart_event( $cart_item_key, $product_id, $quantity
 				return;
 			}
 
+			// Cut off cart clones.
 			$cart = WC()->cart;
-			// Check if we're dealing with cloned cart
 			if ( ! isset( $cart->cart_contents[ $cart_item_key ] ) ) {
 				return;
 			}
@@ -736,86 +735,6 @@ public function add_conditional_add_to_cart_event_fragment( $fragments ) {
 			return $fragments;
 		}
 
-
-		/**
-		 * Sets last product added to cart to session when adding to cart a product and redirection to cart is enabled.
-		 *
-		 * @internal
-		 *
-		 * @since 1.10.2
-		 *
-		 * @param string           $redirect URL redirecting to (usually cart)
-		 * @param null|\WC_Product $product the product just added to the cart
-		 * @return string
-		 */
-		public function set_last_product_added_to_cart_upon_redirect( $redirect, $product = null ) {
-
-			// Bail if the session variable has been set or WC()->session is null.
-			if ( ! isset( WC()->session ) || WC()->session->get( 'facebook_for_woocommerce_last_product_added_to_cart', 0 ) > 0 ) {
-				return $redirect;
-			}
-
-			$product_id = 0;
-
-			if ( $product instanceof \WC_Product ) {
-				$product_id = isset( $_POST['variation_id'] ) ?  wc_clean( wp_unslash( $_POST['variation_id'] ) ) : $product->get_id();
-			} elseif ( isset( $_GET['add-to-cart'] ) && is_numeric( wc_clean( wp_unslash( $_GET['add-to-cart'] ) ) ) ) {
-				$product_id = wc_clean( wp_unslash( $_GET['add-to-cart'] ) );
-			}
-
-			WC()->session->set( 'facebook_for_woocommerce_last_product_added_to_cart', (int) $product_id );
-
-			return $redirect;
-
-		}
-
-
-		/**
-		 * Sets last product added to cart to session when adding a product to cart from an archive page and both AJAX adding and redirection to cart are enabled.
-		 *
-		 * @internal
-		 *
-		 * @since 1.10.2
-		 *
-		 * @param null|int $product_id the ID of the product just added to the cart
-		 */
-		public function set_last_product_added_to_cart_upon_ajax_redirect( $product_id = null ) {
-
-			if ( ! $product_id ) {
-				facebook_for_woocommerce()->log( 'Cannot record AddToCart event because the product cannot be determined. Backtrace: ' . print_r( wp_debug_backtrace_summary(), true ) );
-				return;
-			}
-
-			$product = wc_get_product( $product_id );
-
-			if ( $product instanceof \WC_Product ) {
-				WC()->session->set( 'facebook_for_woocommerce_last_product_added_to_cart', $product->get_id() );
-			}
-		}
-
-
-		/**
-		 * Triggers an AddToCart event when redirecting to the cart page.
-		 *
-		 * @internal
-		 */
-		public function inject_add_to_cart_redirect_event() {
-
-			if ( ! $this->is_pixel_enabled() ) {
-				return;
-			}
-
-			$last_product_id = WC()->session->get( 'facebook_for_woocommerce_last_product_added_to_cart', 0 );
-
-			if ( $last_product_id > 0 ) {
-
-				$this->inject_add_to_cart_event( '', $last_product_id, 1, 0 );
-
-				WC()->session->set( 'facebook_for_woocommerce_last_product_added_to_cart', 0 );
-			}
-		}
-
-
 		/**
 		 * Triggers an InitiateCheckout event when customer reaches checkout page.
 		 *

facebook-commerce-pixel-event.php

@@ -285,15 +285,16 @@ public function get_event_script( $event_name, $params, $method = 'track' ) {
 		 * @param string $method     Name of the pixel's fbq() function to call.
 		 */
 		public function inject_event( $event_name, $params, $method = 'track' ) {
-
+			// If we have add to cart redirect enabled, we must defer the events to render them the next page load.
+			$defer = 'yes' === get_option( 'woocommerce_cart_redirect_after_add', 'no' );
 			if ( \WC_Facebookcommerce_Utils::isWoocommerceIntegration() ) {
-				\WC_Facebookcommerce_Utils::wc_enqueue_js( $this->get_event_code( $event_name, self::build_params( $params, $event_name ), $method ) );
+				\WC_Facebookcommerce_Utils::wc_enqueue_js( $this->get_event_code( $event_name, self::build_params( $params, $event_name ), $method ), $defer );
 			} else {
+				// @TODO: if this one is ever used. Doubts have I.
 				printf( $this->get_event_script( $event_name, self::build_params( $params, $event_name ), $method ) ); // phpcs:ignore WordPress.XSS.EscapeOutput.OutputNotEscaped
 			}
 		}
 
-
 		/**
 		 * Gets the JavaScript code to track a conditional event wrapped in <script> tag.
 		 *

includes/fbutils.php

@@ -42,6 +42,90 @@ class WC_Facebookcommerce_Utils {
 			'female' => 1,
 			'unisex' => 1,
 		);
+
+		/**
+		 * A deferred events storage.
+		 *
+		 * @var array
+		 *
+		 * @since x.x.x
+		 */
+		private static $deferred_events = [];
+
+		/**
+		 * Prints deferred events into page header.
+		 *
+		 * @return void
+		 *
+		 * @since x.x.x
+		 */
+		public static function print_deferred_events() {
+			$deferred_events = static::load_deferred_events();
+			if ( ! empty( $deferred_events ) ) {
+				echo '<script>' . implode( PHP_EOL, $deferred_events ) . '</script>'; //phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped --- Printing hardcoded JS tracking code.
+			}
+		}
+
+		/**
+		 * Loads deferred event from the storage.
+		 *
+		 * @return array
+		 *
+		 * @since x.x.x
+		 */
+		private static function load_deferred_events(): array {
+			$transient_key = static::get_deferred_events_transient_key();
+			if ( $transient_key ) {
+				$deferred_events = get_transient( $transient_key );
+				if ( $deferred_events ) {
+					delete_transient( $transient_key );
+					return $deferred_events;
+				}
+			}
+			return array();
+		}
+
+		/**
+		 * Adds event into the list of events to be saved/rendered.
+		 *
+		 * @param string $code Generated JS code string w/o a script tag.
+		 *
+		 * @return void
+		 *
+		 * @since x.x.x
+		 */
+		private static function add_deferred_event( string $code ): void {
+			static::$deferred_events[] = $code;
+		}
+
+		/**
+		 * Saves deferred events into the storage.
+		 *
+		 * @return void
+		 *
+		 * @since x.x.x
+		 */
+		public static function save_deferred_events() {
+			$transient_key = static::get_deferred_events_transient_key();
+			if ( ! empty( static::$deferred_events ) ) {
+				set_transient( $transient_key, static::$deferred_events, 60 * 60 * 24 );
+			}
+		}
+
+		/**
+		 * Returns the transient key for deferred events based on user session.
+		 *
+		 * @return string
+		 *
+		 * @since x.x.x
+		 */
+		private static function get_deferred_events_transient_key(): string {
+			if ( is_object( WC()->session ) ) {
+				return 'pinterest_for_woocommerce_async_events_' . md5( WC()->session->get_customer_id() );
+			}
+			return '';
+		}
+
 		/**
 		 * WooCommerce 2.1 support for wc_enqueue_js
 		 *
@@ -51,9 +135,16 @@ class WC_Facebookcommerce_Utils {
 		 * @param string $code
 		 * @return void
 		 */
-		public static function wc_enqueue_js( $code ) {
+		public static function wc_enqueue_js( $code, $defer = false ) {
 			global $wc_queued_js;
 
+			// Saves for later output with the next page render.
+			if ( $defer ) {
+				static::add_deferred_event( $code );
+				return;
+			}
+
+			// Immediately renders code in the footer.
 			if ( function_exists( 'wc_enqueue_js' ) && empty( $wc_queued_js ) ) {
 				wc_enqueue_js( $code );
 			} else {