protected void TreeBind()
        {
            var categoryIdTitleMap = new Agp2pDataContext().dt_article_category.Where(c => c.channel_id == 6).OrderBy(c => c.sort_id).ToDictionary(c => c.id, c => c.title);

            ddlCategoryId.Items.Clear();
            ddlCategoryId.Items.Add(new ListItem("所有产品", ""));
            ddlCategoryId.Items.AddRange(categoryIdTitleMap.Select(c => new ListItem(c.Value, c.Key.ToString())).ToArray());
            if (categoryId > 0)
            {
                ddlCategoryId.SelectedValue = categoryId.ToString();
            }
        }