Im使用woocommerce筛选器修改电子邮件管理员通知的收据“woocommerce_email_recipient_new_order“我将它们调整为订单计费的状态。为此，有一个方法get\\u billing\\u state（），它可以完美地发送通知，但在管理员中，我遇到了错误：

未捕获错误：在null上调用成员函数get\\u billing\\u state（）。

我假设我可以打电话给账单状态Maualy，以某种方式表达它。

function tm_destinatario_condicionado_wc( $recipient, $order ) {

    $estados = array(
        \'aguascalientes\'        => \'AG\',
        \'baja-california\'       => \'BC\',
        // etc etc ...
    );

    // Get billing state 2 digits
    // This is what is causing the error
    $estado_siglas = $order->get_billing_state();

    // Get the keys of $estados by the value (wich is the 2 digit billing 
    // state) to get state name
    $estado_slug = array_search( $estado_siglas, $estados );

    // Gets the id of a taxonomy related to the state based on the name 
    // obtained from $estados theres a custon field containing the recipients
    $estado_id = get_term_by( \'slug\', $estado_slug, \'estados\' )->term_id;

    // get the custom field with the recipients
    $emails  = get_field( \'sucursal_email\', \'estados_\' . $estado_id ); 

    // Add the custom field content to the recipient
    $recipient .= \', \' . $emails; 

    return $recipient;
}

add_filter( \'woocommerce_email_recipient_new_order\', \'tm_destinatario_condicionado_wc\', 10, 2 );