動態(tài)加載用戶控件至DataList并為用戶控件賦值實(shí)例演示

更新時間：2013年01月10日 16:38:51 作者：

本文借用使用通用的新聞例子演示動態(tài)加載用戶控件至DataList并為用戶控件賦值，感興趣的朋友可以了解下

為了實(shí)現(xiàn)這個演示，Insus.NET使用通用的新聞例子，它類別(目錄)以及文章。在一個頁面，顯示所有類別，每個目錄下顯示最新幾條新聞。

效果如下：

目錄是用DataList控件顯示，而文章標(biāo)題列表是一個用戶控件顯示，這個用戶控件將動態(tài)被加入至DataList。

復(fù)制代碼代碼如下:

 
View Code 
<asp:Repeater ID="Repeater1" runat="server" OnItemDataBound="Repeater1_ItemDataBound"> 
<HeaderTemplate> 
<table cellpadding="5" cellspacing="0" width="100%"> 
</HeaderTemplate> 
<ItemTemplate> 
<tr style="height: 30px; line-height: 10px;"> 
<td> 
$ 
</td> 
<td> 
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# "~/ArticleView.aspx?ID=" & Eval("Article_nbr")%>' ToolTip='<%# Eval("Subject")%>' Target="_blank"></asp:HyperLink> 
</td> 
<td> 
<%# objInsusDateTimeUtility.GetDateTime(Eval("PublicDate"), "yyyy-MM-dd")%> 
</td> 
</tr> 
</ItemTemplate> 
<FooterTemplate> 
</table> 
</FooterTemplate> 
</asp:Repeater> 

復(fù)制代碼代碼如下:

 
View Code 
View Code 
Imports System.Data 
Imports Insus.NET 
Partial Class AscxControls_ArticleList 
Inherits System.Web.UI.UserControl 
Implements ISetValue '繼承接口 
Dim objArticle As New Article() 
Protected objInsusDateTimeUtility As New InsusDateTimeUtility() 
Private _DataSource As Object 
Private _SubjectLength As Integer = 20 
Public WriteOnly Property SubjectLength() As Integer 
Set(ByVal value As Integer) 
_SubjectLength = value 
End Set 
End Property 
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load 
Data_Binding() 
End Sub 
'綁定數(shù)據(jù)至Repeater控件 
Private Sub Data_Binding() 
Me.Repeater1.DataSource = _DataSource 
Me.Repeater1.DataBind() 
End Sub 
Protected Sub Repeater1_ItemDataBound(ByVal sender As Object, ByVal e As RepeaterItemEventArgs) 
Dim objDrv As DataRowView = DirectCast(e.Item.DataItem, DataRowView) 
If e.Item.ItemType = ListItemType.AlternatingItem OrElse e.Item.ItemType = ListItemType.Item Then 
If e.Item.FindControl("HyperLink1") IsNot Nothing Then 
Dim LinkSubject As HyperLink = DirectCast(e.Item.FindControl("HyperLink1"), HyperLink) 
If objDrv("Subject").Length > _SubjectLength Then 
LinkSubject.Text = objDrv("Subject").Substring(0, _SubjectLength) & "..." 
Else 
LinkSubject.Text = objDrv("Subject").ToString() 
End If 
End If 
End If 
End Sub 
'實(shí)現(xiàn)接口 
Public Sub SetValue(str As Object) Implements ISetValue.SetValue 
Me._DataSource = str 
End Sub 
End Class 

上面用戶控件中，有一個接口：

復(fù)制代碼代碼如下:

 
ISetValue 
using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
namespace Insus.NET 
{ 
public interface ISetValue 
{ 
void SetValue(object obj); 
} 
} 

顯示目錄：

復(fù)制代碼代碼如下:

 
View Code 
<asp:DataList ID="DataListCatalog" runat="server" RepeatColumns="2" RepeatDirection="Horizontal" DataKeyField="Catalog_nbr" OnItemDataBound="DataListCatalog_ItemDataBound"> 
<ItemTemplate> 
<div style="padding:2PX; height:25px; background-color:#cbfb25; font-weight:bold; line-height:25PX;"> 
<%# Eval("CatalogName")%> 
</div> 
<asp:PlaceHolder ID="PlaceHolderArticleList" runat="server"></asp:PlaceHolder> 
</ItemTemplate> 
</asp:DataList> 

從數(shù)據(jù)庫獲取數(shù)據(jù)并綁定至目錄的DataList控件。

復(fù)制代碼代碼如下:

 
View Code 
Imports Insus.NET 
Partial Class Index 
Inherits System.Web.UI.Page 
Dim objCatalog As New Catalog() 
Dim objArticle As New Article() 
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load 
If Not IsPostBack Then 
Data_Binding() 
End If 
End Sub 
Private Sub Data_Binding() 
objCatalog.IsActive = True 
Me.DataListCatalog.DataSource = objCatalog.GetByIsActive() 
Me.DataListCatalog.DataBind() 
End Sub 
End Class 

下面是重點(diǎn)，就是OnItemDataBound事件，在這個事件中，需要找到asp:PlaceHolder控件，這個容器將用來加載用戶控件。

復(fù)制代碼代碼如下:

 
Protected Sub DataListCatalog_ItemDataBound(sender As Object, e As DataListItemEventArgs) 
If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then 
'判斷asp:PlaceHolder是否存在 
If e.Item.FindControl("PlaceHolderArticleList") IsNot Nothing Then 
Dim ctllaceHolder As PlaceHolder = DirectCast(e.Item.FindControl("PlaceHolderArticleList"), PlaceHolder) 
'動態(tài)加載用戶控件，并轉(zhuǎn)換為接口。 
Dim objuc As ISetValue = DirectCast(LoadControl("~/AscxControls/ArticleList.ascx"), ISetValue) 
'找到DataList控件的目錄主鍵 
objArticle.Catalog_nbr = Me.DataListCatalog.DataKeys(e.Item.ItemIndex) 
objArticle.Top = 2 
'為用戶控件賦值。 
objuc.SetValue(objArticle.GetArticalTopByCatalog()) 
'加載用戶控件。 
ctllaceHolder.Controls.Add(objuc) 
End If 
End If 
End Sub 