related-posts.php

<div class="column-b">
            <span class="posts-title">Related Articles</span>

             <?php global $post;

                            $cat = get_the_category( $post->ID );

                            if ($cat){
                                $cat_id = $cat[0]->cat_ID;
                            }
                            else{
                                $cat_id = 1; // Тут задается дефолтная категория
                            }

                            $args = array( 'numberposts' => '2', 'category' => $cat_id );
                            $myposts = get_posts( $args );

                            foreach( $myposts as $post ) :    setup_postdata($post); ?>


            <div class="item-post">
                <?php
                    $thumb = get_post_thumbnail_id();
                    $img_url = wp_get_attachment_url( $thumb,'full' ); //get full URL to image (use "large" or "medium" if the images too big)
                    $image = $img_url; //resize & crop the image

                ?>


                <?php if($image) : ?>
                    <div class="blog-item-img"><a href="<?php the_permalink(); ?>"><img alt="<?php the_title(); ?>"  src="<?php echo $image ?>"/></a></div>
                <?php endif; ?>

                <h2>
                    <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
                </h2>

                <p><?php the_category(', ') ?></p>

                <p class="post-desc"><?php echo excerpt(15); ?></p>

            </div>

             <?php endforeach; ?>

</div>