related post

function create_shortcode_related_posts($args, $content) {
        ob_start(); ?> 
        <?php 
            $tags = wp_get_post_terms( get_queried_object_id(), 'category', array('fields' => 'ids') );
            $args = array (
                'post__not_in' => array ( get_queried_object_id() ),
                'posts_per_page'      => 5,
                'orderby'             => 'rand',
                'tax_query' => array (
                    array(
                        'taxonomy' => 'category',
                        'terms'    => $tags
                    ),
                ),
            );
            $tags_query = new wp_query( $args );
            if( $tags_query->have_posts() ) { ?>
            <ul class="related-posts">
                    <?php while( $tags_query->have_posts() ) {
                        $tags_query->the_post(); ?>
                        <li>
                            <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title();  ?></a>
                        </li>
                    <?php }
                    wp_reset_postdata(); ?>
                    </ul>
            <?php } ?> 
        <?php $group_list = ob_get_contents();
        ob_end_clean();
        return $group_list;
}
add_shortcode('related_posts', 'create_shortcode_related_posts');