protected virtual void PrepareModel(ArticleModel model, Article article = null)
        {
            if (model == null)
                throw new ArgumentNullException("model");

            //所有分类
            model.Categories.AddRange(
                _categoryService.GetAllCategory().Select(t => new SelectListItem
                {
                    Text = t.Name,
                    Value = t.Id.ToString(),
                })
            );

            //所有标签
            model.Tags = _articleService.GetAllTag().Select(t => new KeyValueModel
            {
                Text = t.Name,
                Value = t.Id.ToString()
            }).ToList();

            //选中标签
            if (article != null)
            {
                model.SelectedTags = article.Tags.Select(t => t.Id).ToList();
            }
            
        }
        /// <summary>
        /// 删除
        /// </summary>
        /// <param name="article">文章实体</param>
        public virtual void DeleteArticle(Article article)
        {
            if (article == null)
                throw new ArgumentNullException("article");

            _articleRepository.Delete(article);
        }
        /// <summary>
        /// 插入
        /// </summary>
        /// <param name="article">文章实体</param>
        public virtual void InsertArticle(Article article)
        {
            if (article == null)
                throw new ArgumentNullException("article");

            _articleRepository.Insert(article);
        }