仅将 woocommerce_coupon_get_discount_amount 应用于百分比类型的优惠券

Question

我创建了以下函数来覆盖产品价格并为 WooCommerce 提供最大折扣。但是，我似乎无法弄清楚为什么 woocommerce_coupon_get_discount_amount 过滤器适用于所有优惠券。

我试图让它发挥作用的方式是，如果优惠券是百分比优惠券，它将限制该优惠券的总折扣金额。如果优惠券是 fixed_cart 类型，并且填写了我添加的自定义字段 _price_per_product_amt，那么它将更改产品的价格。

如果我的购物车中只有一张优惠券，这两个功能都可以使用。如果我在购物车中有 fixed_cart_coupon，它将更改价格并将优惠券金额设置为 0 美元（优惠券的金额设置为 0 美元）。但是，如果我也添加百分比优惠券，该功能适用​​于百分比优惠券，但它也会向 fixed_cart_coupon 添加折扣金额。它应该只修改购物车中百分比优惠券的折扣金额。

// filter to change discount if over max coupon amount
function filter_woocommerce_coupon_get_discount_amount( $discount, $discounting_amount, $cart_item, $single, $instance ) {

    $cartCoupons = WC()->cart->get_applied_coupons();
    
    foreach ($cartCoupons as $key => $appliedCoupon) {
        $coupon = new WC_Coupon($appliedCoupon);
        $couponType = get_post_meta( $coupon->get_id(), 'discount_type', true );
        if ($couponType == 'percent') {
            $maxCouponAmount = get_post_meta( $coupon->get_id(), '_max_discount', true );
            $excludedProducts = explode(",", get_post_meta( $coupon->get_id(), 'exclude_product_ids', true ));
            $cartLines = count(WC()->cart->get_cart());
            $cartLineItems = WC()->cart->get_cart();

            foreach ($cartLineItems as $cartItem){
                $cartProductID[] = $cartItem['product_id'];

                if (!empty($excludedProducts)) {
                    $cartLinesWithoutExcluded = array_intersect($cartProductID,$excludedProducts);
                } else {
                    $cartLinesWithoutExcluded = $cartProductID;
                }
                $cartLinesWithoutExcluded = count($cartLinesWithoutExcluded);
                $totalCartItems = $cartLines - $cartLinesWithoutExcluded;
                $discount = $maxCouponAmount / $totalCartItems;
            }
        } else {
            $discount = 0.00;
        }

        return $discount;

    }

}

// apply the coupon whether it is max discount or a product price adjustment
function apply_max_amount_or_product_price_adjustment(){

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
    return;

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

    if ( !is_admin() && !wp_is_json_request() ) {
        global $wp, $woocommerce;
        $cartCoupons = WC()->cart->get_applied_coupons();
        foreach ($cartCoupons as $key => $appliedCoupon) {
            $coupon = new WC_Coupon($appliedCoupon);
            $maxCouponAmount = get_post_meta( $coupon->get_id(), '_max_discount', true );
            $excludedProducts = explode(",", get_post_meta( $coupon->get_id(), 'exclude_product_ids', true ));
            $couponType = get_post_meta( $coupon->get_id(), 'discount_type', true );
            // $fixedProductPrice = get_post_meta( $coupon->get_id(), '_adjust_price', true );
            $couponAmount = WC()->cart->get_coupon_discount_amount( $appliedCoupon );

            if (!empty($maxCouponAmount) && $couponType == 'percent' && ($couponAmount > $maxCouponAmount || $couponAmount == $maxCouponAmount)) {
                add_filter( 'woocommerce_coupon_get_discount_amount', 'filter_woocommerce_coupon_get_discount_amount', 10, 5 );
            }

            if ($couponType == 'fixed_cart'){
                $cart = WC()->cart->get_cart();
                $couponProducts = explode(',',get_post_meta( $coupon->get_id(), 'product_ids', true ));
                $fixedPricePerProduct = get_post_meta( $coupon->get_id(), '_price_per_product_amt', true );

                foreach( $cart as $cart_item ) {
                    if (in_array($cart_item['data']->get_parent_id(), $couponProducts)) {
                        $cart_item['data']->set_price( $fixedPricePerProduct );
                    }
                }
            }
        }
    }
}
add_action('woocommerce_before_calculate_totals', 'apply_max_amount_or_product_price_adjustment', 10, 1);

Answer 1

我似乎无法弄清楚为什么 woocommerce_coupon_get_discount_amount 过滤器适用于所有优惠券。

这是因为当您从函数“apply_max_amount_or_product_price_adjustment”添加过滤器“filter_woocommerce_coupon_get_discount_amount”时，它会添加到所有优惠券中。此过滤器稍后会触发，因此您应用或不应用它的条件将不起作用（因为它已被添加）。您应该删除添加过滤器的部分并将您的过滤器设置在此功能之外。

当您添加任何过滤器时，即使在条件内，由于它已添加，因此每次都会添加它，直到它被 remove_filter( ... ) 删除。在您的情况下，您无法在“apply_max_amount_or_product_price_adjustment”中删除_filter，因为它为时过早，并且会为所有优惠券事件“百分比”类型删除它。

但是，如果我也添加百分比优惠券，该功能适用​​于百分比优惠券，但它也会向固定购物车优惠券添加折扣金额

这是因为您循环过滤器“filter_woocommerce_coupon_get_discount_amount”中的所有优惠券，并始终从第一张优惠券返回价值。每次有 $coupon->get_discount_amount() 时都会触发此过滤器，因此它会在结帐时在您的购物车上应用的每张优惠券上触发。您应该删除循环并仅检查当前优惠券。为了更好地理解，您应该将参数“$instance”重命名为“$coupon”，即当前的 WC_Coupon 对象。

您可以查看 WC_Coupon 类并在此处搜索过滤器“woocommerce_coupon_get_discount_amount”（按 ctrl + f 在页面中找到它）：https://github.com/woocommerce/woocommerce/blob/trunk/plugins/woocommerce/includes/class-wc-coupon.php

另外，在你的循环中要小心：

foreach ($cartLineItems as $cartItem){
    $cartProductID[] = $cartItem['product_id'];

    if (!empty($excludedProducts)) {
        $cartLinesWithoutExcluded = array_intersect($cartProductID,$excludedProducts);
    } else {
        $cartLinesWithoutExcluded = $cartProductID;
    }

    $cartLinesWithoutExcluded = count($cartLinesWithoutExcluded);
    $totalCartItems = $cartLines - $cartLinesWithoutExcluded;
    $discount = $maxCouponAmount / $totalCartItems; 
}
// here $discount is the one calculated in last loop like all previous loops didn't exists. (same thing for $cartLinesWithoutExcluded and $totalCarItems)

因为它总是只返回最后一个购物车商品的 $discount。

试试这个代码（未测试）：

add_filter( 'woocommerce_coupon_get_discount_amount', 'filter_woocommerce_coupon_get_discount_amount', 10, 5 ); // add filter for all coupons
// filter to change discount if over max coupon amount
function filter_woocommerce_coupon_get_discount_amount( $discount, $discounting_amount, $cart_item, $single, $coupon ) { 
        // remove loop on applied coupons because you are managing coupon that is currently applied to the cart   
        if ( $coupon->is_type( 'percent' ) ) {
            $maxCouponAmount = get_post_meta( $coupon->get_id(), '_max_discount', true );

            // TRY TO REMOVE THIS FOR TESTING
            // OR TRY TO return $maxCouponAmount to check this value
            if ( empty( $maxCouponAmount ) ) { // do not change coupon discount if no max_discount
                return $discount;
            }
            // ---

            $excludedProducts = explode(",", get_post_meta( $coupon->get_id(), 'exclude_product_ids', true ));
            $cartLines = count(WC()->cart->get_cart());
            $cartLineItems = WC()->cart->get_cart();

            // Changes in your loop
            $cartLinesWithoutExcluded = 0; // *** UPDATE HERE

            foreach ($cartLineItems as $cartItem){
                $cartProductID[] = $cartItem['product_id'];
                if (!empty($excludedProducts)) {
                    $cartLinesWithoutExcluded += count ( array_intersect($cartProductID,$excludedProducts) );
                } else {
                    $cartLinesWithoutExcluded += count ( $cartProductID );
                }
            }
            $totalCartItems = $cartLines - $cartLinesWithoutExcluded;
            $discount = $totalCartItems > 0 ? $maxCouponAmount / $totalCartItems : 0; // Never divide by 0 !
            // end of changes in your loop
        } elseif ( $coupon->is_type( 'fixed_cart' ) ) {
            $discount = 0.00;
        }

        return $discount;

}

// apply the coupon whether it is max discount or a product price adjustment
function apply_max_amount_or_product_price_adjustment(){

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
    return;

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

    if ( !is_admin() && !wp_is_json_request() ) {
        global $wp, $woocommerce;
        $cartCoupons = WC()->cart->get_applied_coupons();
        foreach ($cartCoupons as $key => $appliedCoupon) {
            $coupon = new WC_Coupon($appliedCoupon);
            $maxCouponAmount = get_post_meta( $coupon->get_id(), '_max_discount', true );
            $excludedProducts = explode(",", get_post_meta( $coupon->get_id(), 'exclude_product_ids', true ));
            $couponType = get_post_meta( $coupon->get_id(), 'discount_type', true );
            // $fixedProductPrice = get_post_meta( $coupon->get_id(), '_adjust_price', true );
            $couponAmount = WC()->cart->get_coupon_discount_amount( $appliedCoupon );

            // removed adding filter here

            if ($couponType == 'fixed_cart'){
                $cart = WC()->cart->get_cart();
                $couponProducts = explode(',',get_post_meta( $coupon->get_id(), 'product_ids', true ));
                $fixedPricePerProduct = get_post_meta( $coupon->get_id(), '_price_per_product_amt', true );

                foreach( $cart as $cart_item ) {
                    if (in_array($cart_item['data']->get_parent_id(), $couponProducts)) {
                        $cart_item['data']->set_price( $fixedPricePerProduct );
                    }
                }
            }
        }
    }
}
add_action('woocommerce_before_calculate_totals', 'apply_max_amount_or_product_price_adjustment', 10, 1);

如有必要，请测试和编辑代码。对不起，如果我的解释看起来很混乱，我在半夜写。