Pulling in Related Posts based on Post Type array

Question

I'm trying to create a Related Posts section on my single.php file and I'm using this as a starting point (http://www.wpbeginner.com/wp-tutorials/how-to-display-related-posts-in-wordpress/) and my issue is I don't think this script is calling from custom post types. Just whatever is in the main post area, which has no posts. They're all in the CPT's. What would I adjust to make this work? Here's one thing I tried already that came up with errors.

<div class="relatedposts">  
            <h3>Related posts</h3>  
                <?php  
                    $orig_post = $post array( 'food', 'film', 'music', 'art', 'fashion', 'photography' );
                    global $post;  
                    $tags = wp_get_post_tags($post->ID);  

                    if ($tags) {  
                    $tag_ids = array();  
                    foreach($tags as $individual_tag) $tag_ids[] = $individual_tag->term_id;  
                    $args=array(  
                    'tag__in' => $tag_ids,  
                    'post__not_in' => array($post->ID),  
                    'posts_per_page'=>4, // Number of related posts to display.  
                    'caller_get_posts'=>1  
                );  

                    $my_query = new wp_query( $args );  

                    while( $my_query->have_posts() ) {  
                    $my_query->the_post();  
                ?>  

                <div class="relatedthumb">  
                    <a rel="external" href="<? the_permalink()?>"><?php the_post_thumbnail(array(150,100)); ?><br />  
                    <?php the_title(); ?>  
                    </a>  
                </div>  

                <? }  
                }  
                $post = $orig_post;  
                wp_reset_query();  
                ?>  
            </div>

Answer 1

By default WP_Query() will query posts (unless tax_query is set). You can change this by setting the post_type key in your $args array.

To search for the same post type as is being currently viewed you can do the following:

$args=array(  
    'post_type'        => get_post_type(), //gets the post type of the current 'post'
    'tag__in'          => $tag_ids,  
    'post__not_in'     => array($post->ID),  
    'posts_per_page'   => 4, // Number of related posts to display.  
    'caller_get_posts' => 1  
);