更新 2
根据 "Check if a customer has purchased a specific products in WooCommerce" 回答代码，以下将阻止购买“试用包”产品，如果它已经购买过一次，或者如果任何产品属于定义的产品类别“A”已被购买。
自 Woocommerce 3 以来，您的实际代码已经过时并且存在一些错误......
我使用受wc_customer_bought_product() source code 启发的自定义条件函数来检查客户是否可以购买“免费试用”产品。此函数还将检查产品 ID 或产品类别：
function has_bought_items( $user_id = 0, $product_ids = 0, $categories_slugs = '' ) {
global $wpdb;
$customer_id = $user_id == 0 || $user_id == '' ? get_current_user_id() : $user_id;
$statuses = array_map( 'esc_sql', wc_get_is_paid_statuses() );
if ( is_array( $product_ids ) ) {
$product_ids = implode(',', $product_ids);
}
if ( $product_ids != ( 0 || '' ) ) {
$query_in = "IN ($product_ids)";
}
else {
$categories = is_array( $categories_slugs ) ? implode("','", $categories_slugs) : $categories_slugs;
$query_in = "IN (
SELECT DISTINCT products.ID FROM {$wpdb->prefix}posts AS products
INNER JOIN {$wpdb->prefix}term_relationships as term_rel
ON products.ID = term_rel.object_id
INNER JOIN {$wpdb->prefix}term_taxonomy as term_tax
ON term_rel.term_taxonomy_id = term_tax.term_taxonomy_id
INNER JOIN {$wpdb->prefix}terms as terms
ON term_tax.term_taxonomy_id = terms.term_id
WHERE products.post_status = 'publish'
AND term_tax.taxonomy = 'product_cat'
AND terms.slug IN ('$categories')
)";
}
// Count the number of products
$product_count_query = $wpdb->get_var( "
SELECT DISTINCT COUNT(orders.ID)
FROM {$wpdb->prefix}posts AS orders
INNER JOIN {$wpdb->prefix}postmeta AS order_meta
ON orders.ID = order_meta.post_id
INNER JOIN {$wpdb->prefix}woocommerce_order_items AS order_items
ON orders.ID = order_items.order_id
INNER JOIN {$wpdb->prefix}woocommerce_order_itemmeta AS order_itemmeta
ON order_items.order_item_id = order_itemmeta.order_item_id
WHERE orders.post_status IN ( 'wc-" . implode( "','wc-", $statuses ) . "' )
AND order_meta.meta_key = '_customer_user'
AND order_meta.meta_value = $customer_id
AND order_itemmeta.meta_key IN ( '_product_id', '_variation_id' )
AND order_itemmeta.meta_value $query_in
" );
// Return a boolean value if count is higher than 0
return $product_count_query > 0 ? true : false;
}
您使用上述自定义条件函数重新访问的代码：
// add_filter( 'woocommerce_variation_is_purchasable', 'trial_package_purchasable_once', 10, 2 );
add_filter( 'woocommerce_is_purchasable', 'trial_package_purchasable_once', 10, 2 );
function trial_package_purchasable_once( $purchasable, $product ) {
// HERE set the free trial product Id to be purchased only once (can be an array of Ids too)
$free_trial_id = 50;
// HERE set the specific product category SLUG (could be an array of slugs too)
$categories = array('lettering'); // Only slug terms
if ( $product->get_id() == $free_trial_id ) {
// Check if any item of the specific product category has already been purchased once
if ( has_bought_items( get_current_user_id(), '', $categories ) ) {
return false;
}
// Check if the free trial product has already been purchased once
elseif ( has_bought_items( get_current_user_id(), $free_trial_id ) ) {
return false;
}
}
}
return $purchasable;
}
代码进入您的活动子主题（或活动主题）的 function.php 文件中。经过测试并且可以工作。
要处理产品类别 Term ID 而不是 Term Slugs，请改用以下条件函数：
// For Product category(ies) Id(s)
function has_bought_items( $user_id = 0, $product_ids = 0, $categories_ids = '' ) {
global $wpdb;
$customer_id = $user_id == 0 || $user_id == '' ? get_current_user_id() : $user_id;
$statuses = array_map( 'esc_sql', wc_get_is_paid_statuses() );
if ( is_array( $product_ids ) ) {
$product_ids = implode(',', $product_ids);
}
if ( $product_ids != ( 0 || '' ) ) {
$query_in = "IN ($product_ids)";
}
else {
$categories = is_array( $categories_ids ) ? implode(',', $categories_ids) : $categories_ids;
$query_in = "IN (
SELECT DISTINCT products.ID FROM {$wpdb->prefix}posts AS products
INNER JOIN {$wpdb->prefix}term_relationships as term_rel
ON products.ID = term_rel.object_id
INNER JOIN {$wpdb->prefix}term_taxonomy as term_tax
ON term_rel.term_taxonomy_id = term_tax.term_taxonomy_id
INNER JOIN {$wpdb->prefix}terms as terms
ON term_tax.term_taxonomy_id = terms.term_id
WHERE products.post_status = 'publish'
AND term_tax.taxonomy = 'product_cat'
AND terms.term_id IN ($categories)
)";
}
// Count the number of products
$product_count_query = $wpdb->get_var( "
SELECT DISTINCT COUNT(orders.ID)
FROM {$wpdb->prefix}posts AS orders
INNER JOIN {$wpdb->prefix}postmeta AS order_meta
ON orders.ID = order_meta.post_id
INNER JOIN {$wpdb->prefix}woocommerce_order_items AS order_items
ON orders.ID = order_items.order_id
INNER JOIN {$wpdb->prefix}woocommerce_order_itemmeta AS order_itemmeta
ON order_items.order_item_id = order_itemmeta.order_item_id
WHERE orders.post_status IN ( 'wc-" . implode( "','wc-", $statuses ) . "' )
AND order_meta.meta_key = '_customer_user'
AND order_meta.meta_value = $customer_id
AND order_itemmeta.meta_key IN ( '_product_id', '_variation_id' )
AND order_itemmeta.meta_value $query_in
" );
// Return a boolean value if count is higher than 0
return $product_count_query > 0 ? true : false;
}
对于带有特殊字符的外语来说，这是更好的选择。