Wordpress Snippet: Simple snippet to get the following, previous and related posts of a post of a certain post type

MyModel.php

<?php
	/**
	 * returns a WP_Query instance which generates a list of news items which have the same theme taxonomy as the given post.
	 * If not post is given the global post will be used
	 *
	 * @param null $postId
	 * @param [] $query
	 *
	 * @return WP_Query
	 */
	public static function getRelatedPosts($postId = null, $query = [])
	{
		$post = get_post($postId);

		$postsQueryArgs = array_merge([
			'post_type'      => $post->post_type,
			'posts_per_page' => 4,
			'tax_query'      => [],
			'orderby'        => 'date',
			'order'          => 'DESC',
			'post__not_in'   => [$post->ID]
		], $query);

		// Get all the news themes of the curren post
		$postNewsThemes = wp_get_post_terms($post->ID, THEME_TAXONOMY);

		$firstNewsTheme = null;

		// If the post got a news theme attached
		if (isset($postNewsThemes[0])) {
			// Save the first news theme in a seperate variable so it can be used in the view for later purposes
			$firstNewsTheme = $postNewsThemes[0];

			// the '$recentPostsQueryArgs' variable is used to create a query for the recent posts.
			// We want show all the recent posts which have the same news theme atttached
			$postsQueryArgs['tax_query'] = [
				[
					'taxonomy' => $firstNewsTheme->taxonomy,
					'field'    => 'slug',
					'terms'    => [$firstNewsTheme->slug]
				]
			];
		}

		return new WP_Query($postsQueryArgs);
	}

	public static function getLatestPost($postId = null)
	{
		// Get the latest post using the getRelatedPosts function. But instead of getting a few posts only get the first one
		$relatedPosts = self::getRelatedPosts($postId, [
			'posts_per_page' => 1,
		]);

		// If the first key has a value we've found our latest post
		return isset($relatedPosts->posts[0]) ? $relatedPosts->posts[0] : null;
	}

	public static function getFollowingPost()
	{
		$previousPost = get_previous_post(false, '', THEME_TAXONOMY);

		return !empty($previousPost) ? $previousPost : self::getLatestPost();
	}