Code-Snippets-Functions/Execute a function on a child site/WooCommerce/hide-products-out-of-stock-10-days.txt

// After stock change events, when the product is without stock
function action_woocommerce_no_stock( $wc_get_product ) {
    // Retrieves the date, in localized format.
    $date = wp_date( 'Y-m-d' );
    
    // Update meta
    $wc_get_product->update_meta_data( '_no_stock_date', $date );

    // Save
    $wc_get_product->save();
}
add_action( 'woocommerce_no_stock', 'action_woocommerce_no_stock', 10, 1 );

// When product is saved in WooCommerce backend
function action_woocommerce_admin_process_product_object( $product ) {
    // Get stock quantity
    $stock_quantity = $product->get_stock_quantity();
    
    // Greater than or equal to
    if ( $stock_quantity >= 1 ) {
        // Get meta value
        $no_stock_date = $product->get_meta( '_no_stock_date' );

        // NOT empty
        if ( ! empty ( $no_stock_date ) ) {
            // Update
            $product->update_meta_data( '_no_stock_date', '' );
        }
    }
}
add_action( 'woocommerce_admin_process_product_object', 'action_woocommerce_admin_process_product_object', 10, 1 ); 

// Change the shop query
function action_woocommerce_product_query( $q, $query ) {
    // Returns true when on the product archive page (shop).
    if ( is_shop() ) {
        // Retrieves the date, in localized format.
        $date = wp_date( 'Y-m-d' );
        
        // Date - 10 days
        $date = wp_date( 'Y-m-d', strtotime( $date . ' -10 days' ) );
        
        // Get any existing meta query
        $meta_query = $q->get( 'meta_query' );
        
        // Define an additional meta query 
        $meta_query[] = array(
            'relation'    => 'OR',
            array(
                'key'     => '_no_stock_date',
                'value'   => $date,
                'compare' => '>',
                'type'    => 'date',
            ),
            array(
                'key'     => '_no_stock_date',
                'compare' => 'NOT EXISTS',
                'type'    => 'date',
            )
        );

        // Set the new merged meta query
        $q->set( 'meta_query', $meta_query );
    }
}
add_action( 'woocommerce_product_query', 'action_woocommerce_product_query', 10, 2 );