1 seule categorie sur ma home page

function my_home_category( $query ) {
 if ( $query->is_home() && $query->is_main_query() ) {
 $query->set( 'cat', '1');
 }
}
add_action( 'pre_get_posts', 'my_home_category' );

<?php
/**
 * Voyage Theme functions and definitions
 *
 * @package voyage
 * @subpackage voyage
 * @since Voyage 1.0
 */
function my_home_category( $query ) {
 if ( $query->is_home() && $query->is_main_query() ) {
 $query->set( 'cat', '8');
 }
}
add_action( 'pre_get_posts', 'my_home_category' );
if ( ! defined( 'VOAYGE_THEME_VERSION' ) ) {
 define( 'VOAYGE_THEME_VERSION', '1.3.8' );
}
/** Run voyage_setup() after the 'after_setup_theme' hook */
add_action( 'after_setup_theme', 'voyage_setup' );

if ( ! function_exists( 'voyage_setup' ) ):
/**
 * Sets up theme defaults and registers support for various WordPress features.
 * Note that this function is hooked into the after_setup_theme hook, which runs
 * before the init hook. The init hook is too late for some features, such as indicating
 * support post thumbnails.
 *
 * To override voyage_setup() in a child theme, add your own voyage_setup to your child theme's functions.php file.
 *
 * @uses add_theme_support() To add support for post thumbnails, custom headers and backgrounds, and automatic feed links.
 * @uses register_nav_menus() To add support for navigation menus.
 * @uses add_editor_style() To style the visual editor.
 * @uses load_theme_textdomain() For translation/localization support.
 * @uses register_default_headers() To register the default custom header images provided with the theme.
 * @uses set_post_thumbnail_size() To set a custom post thumbnail size.
 *
 * @since Voyage 1.0
 */

function voyage_setup() {