WooCommerce移除购物车商品问题：已购商品无法加入购物车

Hey there, let's break down why your woocommerce_add_to_cart hook wasn't working and fix this properly.

Why Your Original Code Failed #

The core issues are tied to hook execution timing and logic gaps:

1. Timing mismatch: The woocommerce_add_to_cart hook fires immediately after a product is added to the cart, but WooCommerce hasn't fully persisted the cart changes to the session yet. When you loop through WC()->cart->get_cart() at this point, the newly added item might not be included in the result, or your session-based token/data might not be fully loaded.
2. Incorrect comparison logic: Your original code only checks if the product SKU matches a single $list->int value. If $list is a collection of all purchased SKUs (which it should be), this will only ever match one item instead of checking against all purchased products.
3. Inefficient cart traversal: Looping through the entire cart every time an item is added is unnecessary—you only need to check the item that was just added.

Fix 1: Prevent Adding Purchased Products (Better UX) #

Instead of adding the item and then removing it, use the woocommerce_add_to_cart_validation hook to block the addition entirely. This gives users clearer feedback without the confusing "add-then-remove" behavior:

add_action('woocommerce_add_to_cart_validation', 'block_purchased_products', 10, 3);
function block_purchased_products($passed, $product_id, $quantity) {
    // Use WooCommerce's session handler instead of raw $_SESSION for better compatibility
    $token = WC()->session->get('******token');
    if (!$token) return $passed;

    $dataservice = *******Service::getService('DataService');
    $purchased_skus = $dataservice->getArticleBlacklist($token);
    if (empty($purchased_skus)) return $passed;

    // Get the correct SKU (handles variations too)
    $product = wc_get_product($product_id);
    $sku_int = intval($product->get_sku());

    // Check if the SKU exists in purchased items
    foreach ($purchased_skus as $purchased_item) {
        if ($sku_int === $purchased_item->int) {
            wc_add_notice(__('You’ve already purchased this product and can’t add it again.', 'woocommerce'), 'error');
            return false; // Block the product from being added
        }
    }

    return $passed;
}

Fix 2: Remove Purchased Items After Addition (If You Prefer This Flow) #

If you still need to remove items post-addition, use the woocommerce_add_to_cart hook with parameters that let you target the exact item just added (no full cart loop needed):

add_action('woocommerce_add_to_cart', 'remove_purchased_product_post_add', 10, 6);
function remove_purchased_product_post_add($cart_item_key, $product_id, $quantity, $variation_id, $variation, $cart_item_data) {
    $token = WC()->session->get('******token');
    if (!$token) return;

    $dataservice = *******Service::getService('DataService');
    $purchased_skus = $dataservice->getArticleBlacklist($token);
    if (empty($purchased_skus)) return;

    // Get the SKU of the newly added item
    $target_product = $variation_id ? wc_get_product($variation_id) : wc_get_product($product_id);
    $sku_int = intval($target_product->get_sku());

    // Check and remove if it's a purchased item
    foreach ($purchased_skus as $purchased_item) {
        if ($sku_int === $purchased_item->int) {
            WC()->cart->remove_cart_item($cart_item_key);
            wc_add_notice(__('This product was already purchased and has been removed from your cart.', 'woocommerce'), 'error');
            break;
        }
    }
}

Key Improvements in These Fixes #

• Uses WC()->session instead of raw $_SESSION to align with WooCommerce's session management (avoids issues with uninitialized sessions).
• Targets only the relevant product instead of looping through the entire cart (faster and less error-prone).
• Properly handles product variations to get the correct SKU.
• Provides clear user feedback via WooCommerce notices.

内容的提问来源于stack exchange，提问作者Alex Schwifty