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фильтр не описан

woocommerce_shop_order_search_fields хук-фильтр . WC 1.0

Searches on meta data can be slow - this lets you choose what fields to search.
3.0.0 added _billing_address and _shipping_address meta which contains all address data to make this faster. This however won't work on older orders unless updated, so search a few others (expand this using the filter if needed).

Использование

add_filter( 'woocommerce_shop_order_search_fields', 'filter_function_name_3064' );
function filter_function_name_3064( $array ){
	// filter...

	return $array;
}
$array
-

Где вызывается хук

WC_Order_Data_Store_CPT::search_orders()
woocommerce_shop_order_search_fields
woocommerce/includes/data-stores/class-wc-order-data-store-cpt.php 485-492
'wc_clean', apply_filters(
	'woocommerce_shop_order_search_fields', array(
		'_billing_address_index',
		'_shipping_address_index',
		'_billing_last_name',
		'_billing_email',
	)
)

Где используется хук (в ядре WC)

Не используется.