This Gist is a companion to a post on the Episerver Social blog called "Getting Started with Comments": http://world.episerver.com/blogs/chris-banner/dates/2017/5/getting-started-with-comments/. It demonstrates the fundamentals of working with Comments in Episerver Social.

MyPageController.cs

public class MyPageController : ContentController<MyContent>
{
	private readonly ICommentService commentService;

	public MyPageController()
	{
		commentService = EPiServer.ServiceLocation.ServiceLocator.Current.GetInstance<ICommentService>();
	}

	// ...

	private void SubmitComment(PageData page, string body)
	{
		// 1. Construct the comment, defining its Body, Author, and Parent
		
		var comment = new Comment(
			CreateReferenceFor(page),
			CreateReferenceFor(HttpContext.Current.User.Identity),
			body,
			true
		);
		
		// 2. Submit the comment to Episerver Social.
		
		commentService.Add(comment);
		
	}

	private void SubmitReply(CommentId parentCommentId, string body)
	{
		// Convert the CommentId of the parent Comment into a Reference.
		
		var parentCommentReference = parentCommentId.ToReference();
		
		 // Construct the comment, defining its Body, Author, and Parent
		
		var comment = new Comment(
			parentCommentReference,
			CreateReferenceFor(HttpContext.Current.User.Identity),
			body,
			true
		);
		
		// Submit the comment to Episerver Social.
		
		commentService.Add(comment);
	}

	private ResultPage<Comment> RetrieveComments(Reference parent, int pageOffset = 0, int pageSize = 10)
	{
		// Define the criteria by which Comments should be retrieved
		
		var criteria = new Criteria<CommentFilter>()
		{
			Filter = new CommentFilter
			{
				Parent = parent
			},
			PageInfo = new PageInfo
			{
				PageOffset = pageOffset,
				PageSize = pageSize
			}
		};
		
		// Retrieve the Comments from Episerver Social
		
		return commentService.Get(criteria);
	}

	private ResultPage<Comment> RetrieveAllComments(PageData page, int pageSize = 10)
	{
		// Define the criteria by which Comments should be retrieved
		
		var criteria = new Criteria<CommentFilter>()
		{
			Filter = new CommentFilter
			{
				Ancestor = CreateReferenceFor(page)
			},
			PageInfo = new PageInfo
			{
				PageSize = pageSize
			}
		};
		
		// Retrieve the Comments from Episerver Social
		
		return commentService.Get(criteria);
	}

	private Reference CreateReferenceFor(PageData page)
	{
		return Reference.Create(page.ContentGuid.ToString());
	}
		
	private Reference CreateReferenceFor(IIdentity user)
	{        
		return user.IsAuthenticated 
			? Reference.Create(user.Name)
			: Reference.Create("Anonymous");
	}
}