public UpdatePostStatus UpdatePost(EditPostModel postModel)
        {
            Post selectedPost = _posts.Find(postModel.PostId);

            int count = selectedPost.Labels.Count;
            for (int i = 0; i < count; i++)
            {
                selectedPost.Labels.Remove(selectedPost.Labels.ElementAt(i));
                count--;
            }

            selectedPost.Labels = postModel.Labels;

            selectedPost.DownloadLinks = postModel.DownloadLinks;

            selectedPost.Body = postModel.PostBody;
            selectedPost.Book.Author = postModel.Book.Author;
            selectedPost.Book.ISBN = postModel.Book.ISBN;
            selectedPost.Book.Language = postModel.Book.Language;
            selectedPost.Book.Name = postModel.Book.Name;
            selectedPost.Book.Page = postModel.Book.Page;
            selectedPost.Book.Year = postModel.Book.Year;
            selectedPost.Book.Description = postModel.Book.Description;
            selectedPost.Book.Publisher = postModel.Book.Publisher;

            selectedPost.Book.Image.Description = postModel.BookImage.Description;
            selectedPost.Book.Image.Path = postModel.BookImage.Path;
            selectedPost.Book.Image.Title = postModel.BookImage.Title;

            selectedPost.CommentStatus = postModel.PostCommentStatus;
            selectedPost.Description = postModel.PostDescription;
            selectedPost.Keyword = postModel.PostKeyword;
            selectedPost.ModifiedDate = postModel.ModifiedDate;
            selectedPost.Status = postModel.PostStatus;
            selectedPost.Title = postModel.PostTitle;

            return UpdatePostStatus.Successfull;
        }

HasOptional(x => x.UserMetaData).WithRequired(x => x.User).WillCascadeOnDelete(false);