WooCommerce按购物车金额赠礼功能故障求助

原代码核心问题分析 #

1. 礼品ID未正确赋值：使用未定义变量而非实际产品ID
2. 赠礼识别逻辑错误：通过不存在的数组键名判断礼品，而非产品ID
3. 价格设置对象错误：未指向购物车项的产品数据对象
4. 无赠礼身份标记：每次刷新购物车重复添加礼品，导致数量递增
5. 满额逻辑错误：金额超过120时错误移除礼品1
6. 小计计算偏差：未排除赠礼金额，导致满额判断不准确

修复后的完整代码 #

function custom_add_free_gifts_based_on_cart_total( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
        return;
    }

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 ) {
        return;
    }

    // 配置区：替换为实际的礼品ID和满额阈值
    $free_product_ids = [
        'gift1' => 6215, // 礼品1的产品ID
        'gift2' => 7912  // 礼品2的产品ID
    ];
    $thresholds = [
        'min_gift1' => 80,
        'min_both_gifts' => 120
    ];

    // 初始化变量
    $cart_subtotal = 0;
    $existing_gifts = [
        'gift1' => false,
        'gift2' => false
    ];
    $gift_keys = [
        'gift1' => '',
        'gift2' => ''
    ];

    // 遍历购物车，计算有效小计并识别赠礼
    foreach ( $cart->get_cart() as $cart_item_key => $cart_item ) {
        $product_id = $cart_item['product_id'];
        $is_free_gift = isset( $cart_item['is_free_gift'] ) && $cart_item['is_free_gift'];

        // 标记赠礼并强制价格为0
        if ( $product_id === $free_product_ids['gift1'] && $is_free_gift ) {
            $existing_gifts['gift1'] = true;
            $gift_keys['gift1'] = $cart_item_key;
            $cart_item['data']->set_price( 0 );
            $cart_item['line_total'] = 0;
            $cart_item['line_tax'] = 0;
        } elseif ( $product_id === $free_product_ids['gift2'] && $is_free_gift ) {
            $existing_gifts['gift2'] = true;
            $gift_keys['gift2'] = $cart_item_key;
            $cart_item['data']->set_price( 0 );
            $cart_item['line_total'] = 0;
            $cart_item['line_tax'] = 0;
        } else {
            // 仅累加非赠礼的金额到有效小计
            $cart_subtotal += $cart_item['line_total'] + $cart_item['line_tax'];
        }
    }

    // 执行赠礼逻辑
    // 1. 金额低于80：移除所有赠礼
    if ( $cart_subtotal < $thresholds['min_gift1'] ) {
        $existing_gifts['gift1'] && $cart->remove_cart_item( $gift_keys['gift1'] );
        $existing_gifts['gift2'] && $cart->remove_cart_item( $gift_keys['gift2'] );
    }
    // 2. 金额80-120：保留礼品1，移除礼品2
    elseif ( $cart_subtotal >= $thresholds['min_gift1'] && $cart_subtotal < $thresholds['min_both_gifts'] ) {
        !$existing_gifts['gift1'] && $cart->add_to_cart( $free_product_ids['gift1'], 1, 0, [], [ 'is_free_gift' => true ] );
        $existing_gifts['gift2'] && $cart->remove_cart_item( $gift_keys['gift2'] );
        $existing_gifts['gift1'] && $cart->set_quantity( $gift_keys['gift1'], 1 );
    }
    // 3. 金额≥120：保留礼品1和礼品2
    elseif ( $cart_subtotal >= $thresholds['min_both_gifts'] ) {
        !$existing_gifts['gift1'] && $cart->add_to_cart( $free_product_ids['gift1'], 1, 0, [], [ 'is_free_gift' => true ] );
        !$existing_gifts['gift2'] && $cart->add_to_cart( $free_product_ids['gift2'], 1, 0, [], [ 'is_free_gift' => true ] );
        $existing_gifts['gift1'] && $cart->set_quantity( $gift_keys['gift1'], 1 );
        $existing_gifts['gift2'] && $cart->set_quantity( $gift_keys['gift2'], 1 );
    }
}
add_action( 'woocommerce_before_calculate_totals', 'custom_add_free_gifts_based_on_cart_total', 10, 1 );

关键修复说明 #

• 赠礼身份标记：添加礼品时传入'is_free_gift' => true元数据，准确区分系统赠礼和用户自行添加的产品，避免重复添加
• 强制价格为0：同时设置产品价格、行总计、行税费为0，确保购物车页面显示的subtotal为0
• 有效小计计算：仅累加非赠礼的金额，避免赠礼干扰满额判断逻辑
• 数量控制：在对应逻辑分支中强制礼品数量为1，防止刷新时数量递增
• 修复满额逻辑：修正原代码中超过120时移除礼品1的错误，改为同时保留两款礼品

内容的提问来源于stack exchange，提问作者Giam