为单个文章设置有效期，到期自动下线

代码放在 func.php 里，然后在后台编辑或新建文章

参照上图右下角，有一个文章有效期，往死里戳

保存或更新后，前台对应文章就会有一个倒计时。时间一到，自动进入回收站。

//文章有效期
CSF::createMetabox('post_validity_options', array(
    'title'     => '文章有效期',
    'post_type' => ['post', 'page', 'forum_post'],
    'context'   => 'side',
    'data_type' => 'unserialize',
));
CSF::createSection('post_validity_options', array(
    'fields' => array(
        array(
            'id'       => 'post_validity_time',
            'type'     => 'date',
            'desc'     => '设置内容的有效期，请确保格式正确，例如：<code>2020-10-10 23:59:59</code></br>到期后将会自动删除此此内容',
            'settings' => array(
                'dateFormat'  => 'yy-mm-dd 23:59:59',
                'changeMonth' => true,
                'changeYear'  => true,
            ),
        ),
    ),
));

add_filter('the_content', 'zib_c_the_content_asdfsdf');
function zib_c_the_content_asdfsdf($content)
{
    $post_id = get_the_ID();
    $time    = get_post_meta($post_id, 'post_validity_time', true);

    if ($time) {
        $end_time = date("m/d/Y H:i:s", strtotime($time));
        $over     = '<script type="text/javascript">window.location.reload()</script>';
        $content  = '<div class="badg c-red block mb20"><i class="fa fa-clock-o mr10"></i>当前内容将于<span class="" data-over-text="' . esc_attr($over) . '"  data-countdown="' . $end_time . '"></span>后失效</div>' . $content;
    }

    return $content;
}

add_action('template_redirect', 'zib_c_template_redirect_sadfasdfkjlaksdf');
function zib_c_template_redirect_sadfasdfkjlaksdf()
{
    if (is_single()) {
        $post_id = get_the_ID();
        $time    = get_post_meta($post_id, 'post_validity_time', true);

        if ($time && strtotime($time) < strtotime(current_time('Y-m-d H:i:s'))) {

            //执行删除文章
            wp_trash_post($post_id);

            wp_safe_redirect(home_url());
            exit;
        }

    }
}