SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://www.progress.com/documentation/sitefinity-cms/for-developers-create-comments

CreateNewsComment2.cs

using System;
using System.Linq;
using Telerik.Sitefinity.Modules.News;
using Telerik.Sitefinity.News.Model;
using Telerik.Sitefinity.Services;
using Telerik.Sitefinity.Services.Comments;
using Telerik.Sitefinity.Services.Comments.Proxies;
using Telerik.Sitefinity.Web.UI;

namespace Telerik.Sitefinity.Documentation.CodeSnippets.DevGuide.SitefinityEssentials.Modules.Comments
{
    public partial class CommentsSnippets
    {
        public static IComment CreateNewsComment(Guid newsItemId, string content, IAuthor author, string ip)
        {
            NewsManager manager = NewsManager.GetManager();

            // Get the news item
            NewsItem newsItem = manager.GetNewsItem(newsItemId);

            //Gets an instance of the comment service
            var cs = SystemManager.GetCommentsService();
            var language = SystemManager.CurrentContext.Culture.Name;
            var threadKey = ControlUtilities.GetLocalizedKey(newsItemId, language);

            CommentsSnippets.EnsureNewsThreadExists(threadKey, author, newsItem.Title, manager, language, cs);

            //new comment is created via the CommentProxy
            var commentProxy = new CommentProxy(content, threadKey, author, ip);

            //set the status of the commentProxy to published. By default it is WaitingForApproval
            commentProxy.Status = StatusConstants.Published;

            var comment = cs.CreateComment(commentProxy);

            return comment;
        }

        /// <summary>
        /// Ensures the news thread exists.
        /// </summary>
        /// <param name="threadKey">The thread key.</param>
        /// <param name="author">The author.</param>
        /// <param name="threadTitle">The thread title.</param>
        /// <param name="manager">The manager.</param>
        /// <param name="language">The language.</param>
        /// <param name="cs">The cs.</param>
        private static void EnsureNewsThreadExists(string threadKey, IAuthor author, string threadTitle, NewsManager manager, string language, ICommentService cs)
        {
            ThreadFilter threadFilter = new ThreadFilter();
            threadFilter.ThreadKey.Add(threadKey);
            var thread = cs.GetThreads(threadFilter).SingleOrDefault();

            if (thread == null)
            {
                var groupKey = ControlUtilities.GetUniqueProviderKey(typeof(NewsManager).FullName, manager.Provider.Name);

                CommentsSnippets.EnsureNewsGroupExists(groupKey, author, cs);

                var culture = SystemManager.CurrentContext.AppSettings.GetCultureByName(language);

                var threadProxy = new ThreadProxy(threadTitle, typeof(NewsItem).FullName, groupKey, author, culture) { Key = threadKey };
                thread = cs.CreateThread(threadProxy);
            }
        }

        /// <summary>
        /// Ensures the news group exists.
        /// </summary>
        /// <param name="groupKey">The group key.</param>
        /// <param name="author">The author.</param>
        /// <param name="cs">The cs.</param>
        private static void EnsureNewsGroupExists(string groupKey, IAuthor author, ICommentService cs)
        {
            GroupFilter groupFilter = new GroupFilter();
            groupFilter.GroupKey.Add(groupKey);
            var group = cs.GetGroups(groupFilter).SingleOrDefault();

            if (group == null)
            {
                var groupProxy = new GroupProxy("Group title", "news items in provider", author) { Key = groupKey };
                group = cs.CreateGroup(groupProxy);
            }
        }
    }
}