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[zhongkeruanjian]

昨天那个自定义的派生于DATALIST的可分页的SUNDATALIST的问题
你建议我看的例子，我已经看了，谢谢！，
今天重载了RENDER，
如下：
override protected void Render(HtmlTextWriter writer)
{

RenderContents(writer);
btnPrev.RenderControl(writer);

btnMore.RenderControl(writer);

}
我在重载的 CreateControlHierarchy 方法里
添加了两个按钮控件
如下：
override protected void CreateControlHierarchy(bool useDataSource)
{
base.CreateControlHierarchy(useDataSource);
btnPrev = new ImageButton();

btnPrev.Click += new ImageClickEventHandler(PreviousClicked);
Controls.Add(btnPrev);

btnMore = new ImageButton();

btnMore.Click += new ImageClickEventHandler(MoreClicked);
Controls.Add(btnMore);
}

问题解决！
但是我想不通，为什么在CreateControlHierarchy 方法里添加的两个按钮控件
在DATALIST.RENDER()里会出现类型转换无效这个问题呢？
我重载的RENDER里我自己为什么还要手工RENDER按钮呢？
请指教！

[saucer]

I was wrong, inside DataList.Render method, it does some preparation (like applying styles) on the controls, i.e., Items, it probably tries to cast your buttons to DataListItem, but failed

it was ok in the above code of yours because you called
RenderContents(writer);

and bypassed the other methods

[saucer]

try the following:

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace CSDNControls
{
/// <summary>
/// Summary description for MyDataList.
/// </summary>
[ToolboxData("<{0}:MyDataList runat=server></{0}:MyDataList>")]
public class MyDataList : System.Web.UI.WebControls.DataList
{
Button btnPrev, btnNext;
protected override void CreateControlHierarchy(bool useDataSource)
{
base.CreateControlHierarchy(useDataSource);

DataListItem dli = new DataListItem(0, ListItemType.Item);

btnPrev = new Button();
btnPrev.Text = "Previous";
btnPrev.Click += new EventHandler(Button_Clicked);
dli.Controls.Add(btnPrev);

btnNext = new Button();
btnNext.Text = "Next";
btnNext.Click += new EventHandler(Button_Clicked);
dli.Controls.Add(btnNext);

Controls.Add(dli);
}

private void Button_Clicked(Object sender, EventArgs e)
{
Button btn = (Button)sender;
Page.Response.Write(btn.Text + " is clicked");
}

protected override void Render (HtmlTextWriter writer)
{
base.Render(writer);
//you still have to call the following, since the base.Render will not render them
btnPrev.RenderControl(writer);
btnNext.RenderControl(writer);
}
}
}

[saucer]

I forgot the details, but if you have used
Controls.Add(btnPrev);

then you shouldn't need to do
btnPrev.RenderControl(writer);

that is, you don't need to override Render at all

[wjcking]

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