避免在 WooCommerce 函数中出现错误“调用成员函数 get_cart()…”

Question

在以前确实有效的代码上收到错误，但现在它阻止我在 wordpress 中编辑页面（当我尝试编辑页面时，它表明存在严重错误）。

下面的代码基本上会根据相关产品是否在购物车中来更改添加到购物车按钮的文本。

下面的代码和下面的错误异常：

function woocommerce_custom_add_to_cart_text($add_to_cart_text, $product ) {
    global $woocommerce;
    // Get cart
    $cart_items = $woocommerce->cart->get_cart();

    foreach ( $cart_items as $cart_item_key => $cart_item ) {
        // Get product id in cart
        $_product_id = $cart_item['product_id'];
 
        if ( $product->get_id() == $_product_id ) {
            $add_to_cart_text = 'Already in cart';
        }
    }

    return $add_to_cart_text;
  
}
add_filter( 'woocommerce_product_add_to_cart_text', 'woocommerce_custom_add_to_cart_text', 10, 2 );

错误异常：

An error of type E_ERROR was caused in line 3 of the file /home4/metisonl/public_html/staging/4326/wp-content/plugins/code-snippets/php/snippet-ops.php(446) : eval()'d code. Error message: Uncaught Error: Call to a member function get_cart() on null in /home4/metisonl/public_html/staging/4326/wp-content/plugins/code-snippets/php/snippet-ops.php(446) : eval()'d code:3
Stack trace:
#0 /home4/metisonl/public_html/staging/4326/wp-includes/class-wp-hook.php(287): woocommerce_custom_add_to_cart_text('Add to cart', Object(WC_Product_Simple))
#1 /home4/metisonl/public_html/staging/4326/wp-includes/plugin.php(206): WP_Hook->apply_filters('Add to cart', Array)
#2 /home4/metisonl/public_html/staging/4326/wp-content/plugins/woocommerce/includes/class-wc-product-simple.php(62): apply_filters('woocommerce_pro...', 'Add to cart', Object(WC_Product_Simple))
#3 /home4/metisonl/public_html/staging/4326/wp-content/plugins/woo-gutenberg-products-block/src/BlockTypes/AbstractProductGrid.php(473): WC_Product_Simple->add_to_cart_text()
#4 /home4/metisonl/public_html/staging/4326/wp-content/plugins/woo-gutenberg-products-block/src/BlockTypes/AbstractProductGrid.php(446): Automattic\WooCommerce\Blocks\BlockTypes\Abstra

Answer 1

已更新 ...您需要检查购物车对象是否存在且购物车不为空，因此请尝试以下操作以避免此类错误：

add_filter( 'woocommerce_product_add_to_cart_text', 'filter_product_add_to_cart_text', 10, 2 );
function filter_product_add_to_cart_text( $add_to_cart_text, $product ) {
    if ( ! WC()->cart && WC()->cart->is_empty() ) 
        return $add_to_cart_text;

    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $cart_item ) {
        // Get product id in cart
        $_product_id = $cart_item['product_id'];
 
        if ( $product->get_id() == $_product_id ) {
            return __('Already in cart');
        }
    }
    return $add_to_cart_text;
}

代码位于活动子主题（或活动主题）的functions.php 文件中。经过测试并且可以工作。