记事本

1. 创建一个用户控件。

namespace Northwind.WebSite.UserControls
{
    public partial class CategoryDetail : System.Web.UI.UserControl
    {
        private Category category;
        public Category Category
        {
            set { category = value; }
            get { return category; }
        }
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void Page_PreRender(object sender, EventArgs e)
        {
            GridViewProducts.DataSource = category.Products;
            GridViewProducts.DataBind();
            LableCategoryName.Text = category.CategoryName;
            LabelTotalPrice.Text = string.Format("Total price: {0}",
                category.Products.Sum(p =>
                    p.UnitPrice * (p.UnitsInStock + p.UnitsOnOrder)));
        }
        public void ExpandCollapsiblePanel()
        {
            CollapsiblePanelExtender1.Collapsed = false;
        }
    }
}

2. 实现ITemplate。

namespace Northwind.WebSite.TemplateControl
{
    public class CategoryDetailTemplate : ITemplate
    {
        public void InstantiateIn(Control container)
        {
            CategoryDetail detail = (CategoryDetail)BuildManager.
                CreateInstanceFromVirtualPath("~/UserControls/CategoryDetail.ascx", typeof(CategoryDetail));
            container.DataBinding += delegate(object sender, EventArgs e)
            {
                IDataItemContainer container1 = container as IDataItemContainer;

                detail.Category = (Category)container1.DataItem;
                if (container1.DataItemIndex == 0)
                {
                    detail.ExpandCollapsiblePanel();
                }
            };
            container.Controls.Add(detail);
        }
    }
}

3. 动态加载。

namespace Northwind.WebSite
{
    public partial class ProductsByCategory : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Repeater1.ItemTemplate = new CategoryDetailTemplate();
            if (!IsPostBack)
            {
                var ds = Category.GetCategories();
                Repeater1.DataSource = ds;
                Repeater1.DataBind();
            }
        }
    }
}