php - 如果条件满足(购物车中的有限产品太多)Woocommerce 时重定向到页面的自定义功能

Question

我为 WooCommerce 制作了一个自定义插件。我试图限制客户可以从特定类别购买的产品数量。大多数都有效，但是一旦满足条件，我就无法让它触发重定向功能。
这是我的代码:

add_action( 'wp', 'check_limited_products_in_cart');

function check_limited_products_in_cart () {
    // holds checks for all products in cart to see if they're in our category
    $category_checks = array();
    $limited_product_count = 1;

    // check each cart item for our category
    foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {

        $product = $cart_item['data'];
        $product_in_cat = false;

        // replace 'instant-print' with your category's slug
        if ( has_term( 'instant-print', 'product_cat', $product->id ) ) {
            $product_in_cat = true;
        }

        array_push( $category_checks, $product_in_cat );
    }

    $filtered_array = count(array_filter($category_checks));
    if ($filtered_array >= $limited_product_count) {
        redirect_limited_products_page(); // this bit seems to be failing
    }
}

function redirect_limited_products_page () {
    $error_page = '/error';
    $target_url = $error_page; // construct a target url
    wp_redirect($target_url, 301); // permanent redirect
    exit();
}

我认为我的第二个功能是抛出太多重定向。该页面正在翻腾，因此我从未看到任何有用的控制台信息。
我已经尝试过各种迭代，比如尝试在一个 block 中运行整个函数(抛出相同的错误)，然后提升 $filtered_array作为全局变量，所以我可以从第二个函数访问它，但我也无法让它工作。
非常感谢任何帮助。
编辑
好一点的进步。
我现在回来了:

add_action( 'woocommerce_before_cart', 'check_limited_products_in_cart');

function check_limited_products_in_cart () {
    // holds checks for all products in cart to see if they're in our category
    $category_checks = array();
    $limited_product_count = 1;

    // check each cart item for our category
    if( ! is_admin() ) {
        foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {

            $product = $cart_item['data'];
            $product_in_cat = false;

            // replace 'instant-print' with your category's slug
            if ( has_term( 'instant-print', 'product_cat', $product->id ) ) {
                $product_in_cat = true;
            }

            array_push( $category_checks, $product_in_cat );
        }
    }

    $filtered_array = count(array_filter($category_checks));
    if ($filtered_array >= $limited_product_count) {
        echo '<p>condition met</p>';
        redirect_limited_products_page();
    }
}

function redirect_limited_products_page () {
    echo '<p>Redirect page</p>';
    $error_page = '/error';
    $target_url = $error_page; // construct a target url
    wp_redirect($target_url, 301); // permanent redirect
    exit();
}

在我制作一个全局 wp 函数之前，它会在任何地方渲染并可能解释了重定向循环。
所以现在当我将另一个产品添加到购物车时，我看到 condition met以及 Redirect page但出现以下错误:

Warning: Cannot modify header information - headers already sent by (output started at my-site-url\wp-includes\class.wp-styles.php:290) in my-site-url\wp-includes\pluggable.php on line 1296

Warning: Cannot modify header information - headers already sent by (output started at my-site-url\wp-includes\class.wp-styles.php:290) in my-site-url\wp-includes\pluggable.php on line 1299

所以这感觉更接近了。
** 进一步更新 **
在阅读了有关标题的问题后，我尝试整理我的文件，确保没有空格和格式错误的标签。我删除了关闭的 php 标记并检查了我的 linting。我认为主要的罪魁祸首是重定向函数中的 exho 语句引发了标题问题。你可以在这里看到。

我正在检查当前的受限产品数量与篮子中当前受限产品的数量。现在看来重定向永远不会触发，所以我的假设是 add_action( 'woocommerce_before_cart', ...)可能需要 add_filter ('woocommerce_add_to_cart_validation', ...)这似乎也不起作用。即使条件显示为满足并且不会触发重定向，这些项目也会添加到购物车项目中。所以我不确定我是否试图 Hook 错误的功能。

<?php

$error_page = '/product-limit-reached';

    add_action( 'woocommerce_before_cart', 'check_limited_products_in_cart');

    function check_limited_products_in_cart () {
        // holds checks for all products in cart to see if they're in our category
        $category_checks = array();
        $limited_product_count = 1;

        // check each cart item for our category
        if( ! is_admin() ) {
            foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {

                $product = $cart_item['data'];
                $product_in_cat = false;

                // replace 'instant-print' with your category's slug
                if ( has_term( 'instant-print', 'product_cat', $product->id ) ) {
                    $product_in_cat = true;
                }

                array_push( $category_checks, $product_in_cat );
            }
        }

        $filtered_array = count(array_filter($category_checks));
        if ($filtered_array >= $limited_product_count) {
            echo '<p>condition met</p><p>Limited product count: ' . $limited_product_count. '</p><p>Limited products in cart: ' . $filtered_array. '</p>';
            redirect_limited_products_page();
        }
    }

    function redirect_limited_products_page () {
        $target_url = $error_page; // construct a target url
        wp_redirect($target_url, 301); // permanent redirect
        // exit();
    }

Answer 1

是的，您需要使用 woocommerce_add_to_cart_validation Hook 。
我们可以在将商品添加到购物车时进行检查。如果检查失败，则商品不会进入购物车，并且会向用户显示错误。
就像这样:

function filter_woocommerce_add_to_cart_validation( $true, $product_id, $request_quantity, $variation_id = '', $request_variation = '' ) { 
    // holds checks for all products in cart to see if they're in our category
    $category_checks = 0;
    $limited_product_count = 1;
    $limited_slug = 'instant-print'; //replace 'instant-print' with your category's slug

    // check each cart item for our category
    if( ! is_admin() ) {
        foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {
            $product = $cart_item['data'];

            if ( has_term( $limited_slug, 'product_cat', $product->id ) ) {
                $category_checks += $cart_item['quantity'];
            }
        }
    }

    // We also check the item that the user is trying to add to cart
    if ( has_term( $limited_slug, 'product_cat', $product_id ) ) {
        $category_checks += $request_quantity;
    }

    if ($category_checks >= $limited_product_count) {
        $notice = '<p>condition met</p><p>Limited product count: ' . $limited_product_count. '</p><p>Limited products in cart: ' . $category_checks. '</p>';
        wc_add_notice( __( $notice, 'textdomain' ), 'error' );
        return false;
    }

    return $true;
}; 

add_filter( 'woocommerce_add_to_cart_validation', 'filter_woocommerce_add_to_cart_validation', 10, 3 );