プラグイン無しでWordPressの投稿ページ・固定ページを個別に複製できるスニペット

/* 記事複製 */
function duplicate_post() {
    global $wpdb;
    if (! ( isset( $_GET['post']) || isset( $_POST['post'])  || ( isset($_REQUEST['action']) && 'duplicate_post' == $_REQUEST['action'] ) ) ) {
        wp_die('No post to duplicate has been supplied!');
    }
 
    // 元ネタの記事IDを取得
    $post_id = (isset($_GET['post']) ? $_GET['post'] : $_POST['post']);
    $post = get_post($post_id);
 
    // 新記事のタイトルの生成 末尾に(Copy)の表示
    $new_post = array(
        'post_title' => $post->post_title . ' (Copy)',
        'post_content' => $post->post_content,
        'post_status' => 'draft',
        'post_date' => current_time('mysql'),
        'post_author' => $post->post_author,
        'post_type' => $post->post_type
    );
 
    // データベースに新記事を挿入
    $new_post_id = wp_insert_post($new_post);
 
    $taxonomies = get_object_taxonomies($post->post_type);
    foreach ($taxonomies as $taxonomy) {
        $post_terms = wp_get_object_terms($post_id, $taxonomy, array('fields' => 'slugs'));
        wp_set_object_terms($new_post_id, $post_terms, $taxonomy, false);
    }
 
    // データの挿入
    $post_meta_infos = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->postmeta WHERE post_id=$post_id");
    if (count($post_meta_infos)!=0) {
        $sql_query = "INSERT INTO $wpdb->postmeta (post_id, meta_key, meta_value) ";
        foreach ($post_meta_infos as $post_meta_info) {
            $meta_key = $post_meta_info->meta_key;
            $meta_value = addslashes($post_meta_info->meta_value);
            $sql_query_sel[]= "SELECT $new_post_id, '$meta_key', '$meta_value'";
        }
        $sql_query.= implode(" UNION ALL ", $sql_query_sel);
        $wpdb->query($sql_query);
    }
 
    // 完了後複製された記事にリダイレクト
    wp_redirect(admin_url('post.php?action=edit&post=' . $new_post_id));
    exit;
}
 
add_action('admin_action_duplicate_post', 'duplicate_post');
 
function add_duplicate_link($actions, $post) {
    if (current_user_can('edit_posts')) {
		$actions['duplicate'] = '<a href="' . wp_nonce_url('admin.php?action=duplicate_post&amp;post=' . $post->ID, basename(__FILE__), 'duplicate_nonce') . '" title="Duplicate this item" rel="permalink">記事の複製</a>';
    }
    return $actions;
}
 
add_filter('post_row_actions', 'add_duplicate_link', 10, 2);

/* 固定ページの複製 */
function duplicate_page() {
    global $wpdb;
    if (! ( isset( $_GET['post']) || isset( $_POST['post'])  || ( isset($_REQUEST['action']) && 'duplicate_page' == $_REQUEST['action'] ) ) ) {
        wp_die('No post to duplicate has been supplied!');
    }

    // ページIDを取得
    $post_id = (isset($_GET['post']) ? $_GET['post'] : $_POST['post']);
    // ページ情報の取得
    $post = get_post($post_id);

    // 新規で固定ページの作成
    $new_page = array(
        'post_title' => $post->post_title . ' (Copy)',
        'post_content' => $post->post_content,
        'post_status' => 'draft',
        'post_date' => current_time('mysql'),
        'post_author' => $post->post_author,
        'post_type' => $post->post_type
    );

    // データベースに固定ページを作成
    $new_page_id = wp_insert_post($new_page);

    // 情報を取得して挿入
    $post_meta_infos = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->postmeta WHERE post_id=$post_id");
    if (count($post_meta_infos)!=0) {
        $sql_query = "INSERT INTO $wpdb->postmeta (post_id, meta_key, meta_value) ";
        foreach ($post_meta_infos as $post_meta_info) {
            $meta_key = $post_meta_info->meta_key;
            $meta_value = addslashes($post_meta_info->meta_value);
            $sql_query_sel[]= "SELECT $new_page_id, '$meta_key', '$meta_value'";
        }
        $sql_query.= implode(" UNION ALL ", $sql_query_sel);
        $wpdb->query($sql_query);
    }

    // 複製完了したらリダイレクト
    wp_redirect(admin_url('post.php?action=edit&post=' . $new_page_id));
    exit;
}

add_action('admin_action_duplicate_page', 'duplicate_page');

function add_duplicate_pagelink($actions, $post) {
    if (current_user_can('edit_pages')) {
		$actions['duplicate'] = '<a href="' . wp_nonce_url('admin.php?action=duplicate_page&amp;post=' . $post->ID, basename(__FILE__), 'duplicate_nonce') . '" title="Duplicate this item" rel="permalink">ページの複製</a>';
    }
    return $actions;
}

add_filter('page_row_actions', 'add_duplicate_pagelink', 10, 2);