Get related news articles by categories.

ContentLocationHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Telerik.Sitefinity.ContentLocations;
using Telerik.Sitefinity.Model;
using Telerik.Sitefinity.Services;

namespace CLane.Helpers
{
	public static class ContentLocationHelper
	{
		/// <summary>
		/// Retrives the page url of where the content item exists
		/// </summary>
		/// <param name="content">Content Item</param>
		/// <returns>Url of page where content item is publish. This does not return the conent items default location.</returns>
		public static string GetDefaultPageUrl(IDataItem content)
		{
			string url = string.Empty;
			IContentItemLocation itemLocation = GetItemLocation(content);

			if (itemLocation != null)
			{
				url = PagesHelper.GetPageUrlById(itemLocation.PageId);
			}
			return url;
		}

		/// <summary>
		/// Gets content items default location
		/// </summary>
		/// <param name="content">Conent item</param>
		/// <returns>Content item location object</returns>
		private static IContentItemLocation GetItemLocation(IDataItem content)
		{
			var locationsService = SystemManager.GetContentLocationService();
			var itemLocation = locationsService.GetItemDefaultLocation(content.GetType(),content.Provider.ToString(), content.Id);
			return itemLocation;
		}

		/// <summary>
		/// Get content items full url path
		/// </summary>
		/// <param name="content">Content item</param>
		/// <returns>Full url path to conent item</returns>
		public static string GetContentItemFullUrl(IDataItem content)
		{
			string url = string.Empty;
			IContentItemLocation itemLocation = GetItemLocation(content);

			if (itemLocation != null)
			{
				url = itemLocation.ItemAbsoluteUrl;
			}
			return url;
		}
	}
}

Detail.NewsDetail.cshtml

@{ List<NewsItem> relatedNews = NewsHelper.GetRelatedNewsByTagsCategories((Model.Item.DataItem as NewsItem), Model.Item.Fields.Tags, Model.Item.Fields.Category);}
	@if (relatedNews != null && relatedNews.Count() > 0)
	{
		<h3 class="pt-3 mb-4">You Might Also Like</h3>
		<div class="row mt-3 news2Col border-bottom border-gray-600  pb-4 mb-4">
			@foreach (var item in relatedNews)
			{

				var navigateUrl = CLane.Helpers.ContentLocationHelper.GetContentItemFullUrl(item);

				<article class="col-md-6 newsItemCol card card-no-border">
					<div class="newsGraphic card-img-top">
							<a href="@navigateUrl"><i class="far fa-newspaper fa-12x"></i></a>
					</div>
					<div class="d-flex mt-2 mb-3">
                        <div class="text-muted">
                            <i class="far fa-calendar-alt"></i>
                            <time pubdate="pubdate">
                                @item.PublicationDate.ToString("MMM d, yyyy")
                            </time>
                        </div>
                        <div class="ml-auto">
                            @Html.CommentsCount(navigateUrl, item)
                        </div>
					</div>
                    <h4>
                        <a class="link-dark" href="@navigateUrl">@item.Title</a>
                    </h4>

					<div class="Col2Summary mt-3">
						@Html.HtmlSanitize(item.Summary)
					</div>
				</article>
			}
		</div>
	}

NewsHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Telerik.OpenAccess;
using Telerik.Sitefinity.GenericContent.Model;
using Telerik.Sitefinity.Model;
using Telerik.Sitefinity.Modules.News;
using Telerik.Sitefinity.News.Model;

namespace CLane.Helpers
{
	public static class NewsHelper
	{
		/// <summary>
		/// Gets other news items that have the same categories/tags
		/// </summary>
		/// <param name="currentNewsItem">Current news item</param>
		/// <param name="tagIds">TrackedList of Guids tags</param>
		/// <param name="categoryIds">TrackedList of Guids categories</param>
		/// <param name="take">How many results to return</param>
		/// <returns>List of news items</returns>
		public static List<NewsItem> GetRelatedNewsByTagsCategories(this IDataItem currentNewsItem, object tagIds, object categoryIds, int take = 2)
		{
			newsManager = NewsManager.GetManager();

			if(tagIds != null || categoryIds != null)
			{
				var listTagIds = tagIds as TrackedList<Guid>;
				var listCategoryIds = categoryIds as TrackedList<Guid>;

				return newsManager.GetNewsItems()
						.AsEnumerable()
						.OrderBy(n => Guid.NewGuid())//Order randomly
						.Where(n => n.Status == ContentLifecycleStatus.Live && n.Visible && n.Id != currentNewsItem.Id)
						.ToList()//Had to ToList as Intersect would not work on the server side
							.Where(n => n.GetValue<IList<Guid>>("Tags").Intersect(listTagIds).Any() || //Filter News by Category or Tag
										n.GetValue<IList<Guid>>("Category").Intersect(listCategoryIds).Any())
							.Take(take)
							.OrderByDescending(n => n.LastModified)
							.ToList();
			}

			return null;
		}

		private static NewsManager newsManager;
		
	}
}