ASP.NET - 在運行時

Question

到中繼器添加行

Public Partial Class _Default 
    Inherits System.Web.UI.Page 

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 

     If Page.IsPostBack = False Then 
      Dim ds1 As New List(Of Link) 

      For i = 1 To x 
       Dim h As New Link 
       ds1.Add(h) 
       h.Text = "ssss" 
       h.URL = "yyyyy" 
      Next 

      rptMenu.DataSource = (ds1) 
     Else 
      rptMenu.DataSource = ViewState("ds1") 
     End If 

     rptMenu.DataBind() 
    End Sub 

    Protected Sub addFeild() 

     Dim ds1 As List(Of Link) = rptMenu.DataSource 
     Dim h As New Link 
     ds1.Add(H) 
     rptMenu.DataBind() 
    End Sub 

    Private Sub Menu_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender 
     ViewState("ds1") = rptMenu.DataSource 
    End Sub 
End Class 

<asp:Repeater ID="rptMenu" runat="server"> 
     <ItemTemplate> 
      <tr> 
       <td><asp:TextBox CssClass="txtBox" ID="txtText" runat="server" Text='<%# Eval("Text") %>'></asp:TextBox></td> 
       <td><asp:TextBox CssClass="txtBox" ID="txtLocation" runat="server" Text='<%# Eval("URL") %>'></asp:TextBox></td> 
       <td><asp:Button ID="btnDelete" runat="server" Text="Delete" /></td> 
      </tr> 
     </ItemTemplate> 
     <FooterTemplate> 
      <tr><td colspan="3"> 
       <asp:Button ID="btnAdd" runat="server" Text="Add" OnClick="addFeild" /> 
      </td></tr></table> 
     </FooterTemplate> 
    </asp:Repeater> 

該代碼添加一行whin我點擊Add

但是，它會刪除所有更改。

如何在不刪除更改的情況下將行添加到中繼器？

Answer 1

爲了解決這個問題，我使用反射來確認哪些是由Repeater完成時，它處理添加行本身，創造一個ExtensibleRepeater從Repeater繼承並允許爲每個更新添加一行。它唯一的問題是你不能使用頁腳概念，因爲在頁腳更新後出現添加的行。

刪除行通過將相關的RepeaterItem的Visible設置爲False來處理。

IIRC之所以會丟失回調數據，是因爲即使在回調函數中調用了DataBind，這也會重置所有現有數據，包括用戶表單數據。

的代碼是專有的，但因爲它是基於的.NET 2.0 Repeater反射器的顯示，我可以告訴你一個編輯的版本：

Imports System.ComponentModel 
Imports System.Security.Permissions 
Imports System.Web 
Imports System.Web.UI 
Imports System.Web.UI.WebControls 

'''====================================================================== 
''' Class: ExtensibleRepeater 
''' 
''' <summary> 
''' A <see cref="Repeater" /> that can be extended by one item. 
''' </summary> 
''' 
''' <remarks> 
''' BUG: If the <see cref="ExtensibleRepeater.FooterTemplate" /> is defined, the additional 
''' item will appear after it! 
''' </remarks> 
''' 
''' <revisionhistory> 
''' 100907 MEH Created based upon reflection on Repeater. 
''' </revisionhistory> 
'''====================================================================== 
<snip> 
Public Class ExtensibleRepeater 
    Inherits Repeater 

Private additionalItem As RepeaterItem 
<snip> 

'''--------------------------------------------------------------------- 
''' Function: AddNew 
''' 
''' <summary> 
''' Adds another <see cref="RepeaterItem"></see> to the <see cref="ExtensibleRepeater"></see>. 
''' </summary> 
''' 
''' <param name="ItemData"> 
''' The data item to associate with the <see cref="RepeaterItem"></see>. 
''' Ignored if <paramref name="UseDataSource"></paramref> is False. 
''' </param> 
''' <param name="UseDataSource"> 
''' Indicates whether to use the specified data source. 
''' </param> 
''' 
''' <returns>The new <see cref="System.Web.UI.WebControls.RepeaterItem"></see>.</returns> 
''' 
''' <exception cref="NotSupportedException">Called more than once.</exception> 
''' 
''' <remarks> 
''' Currently can only be called once. Must be called again after 
''' <see cref="DataBind"></see> is called to recreate the additional item. 
''' </remarks> 
''' 
''' <revisionhistory> 
''' 100907 MEH Created based upon reflection on the protected Repeater.CreateControlHierarchy. 
''' </revisionhistory> 
'''--------------------------------------------------------------------- 
Public Function AddNew(ByVal ItemData As Object, Optional ByVal UseDataSource As Boolean = True) As RepeaterItem 

<snip> 
    If additionalItem IsNot Nothing Then _ 
     Throw New NotSupportedException 

<snip> 
    additionalItem = CreateItem(dataItemCount, itemType, UseDataSource, ItemData) 

<snip> 
    Return additionalItem 
End Function 

'''--------------------------------------------------------------------- 
''' Property: Items 
''' 
''' <summary> 
''' Gets a collection of <see cref="System.Web.UI.WebControls.RepeaterItem"></see> 
''' objects in the <see cref="ExtensibleRepeater"></see>. 
''' </summary> 
''' 
''' <returns> 
''' A collection of <see cref="System.Web.UI.WebControls.RepeaterItem"></see> 
''' objects. The default is an empty <see cref="System.Web.UI.WebControls.RepeaterItemCollection"></see>. 
''' </returns> 
''' 
''' <remarks></remarks> 
''' 
''' <revisionhistory> 
''' 100907 MEH Created. 
''' </revisionhistory> 
'''--------------------------------------------------------------------- 
<snip> 
Public Overrides ReadOnly Property Items() As RepeaterItemCollection 
    Get 
     If additionalItem IsNot Nothing Then 
      Dim newItems As New ArrayList(MyBase.Items) 
      newItems.Add(additionalItem) 
      Return New RepeaterItemCollection(newItems) 
     End If 
     Return MyBase.Items 
    End Get 
End Property 

'''--------------------------------------------------------------------- 
''' Function: CreateItem 
''' 
''' <summary> 
''' Creates a <see cref="System.Web.UI.WebControls.RepeaterItem"></see> 
''' with the specified item type and location within the <see cref="ExtensibleRepeater"></see>. 
''' </summary> 
''' 
''' <param name="ItemIndex"> 
''' The specified location within the <see cref="ExtensibleRepeater"></see> 
''' to place the created item. 
''' </param> 
''' <param name="ItemType"> 
''' A <see cref="System.Web.UI.WebControls.ListItemType"></see> that 
''' represents the specified type of the <see cref="T:System.Web.UI.WebControls.Repeater"></see> 
''' item to create. 
''' </param> 
''' <param name="DataBind"> 
''' Indicates whether to use the specified data source. 
''' </param> 
''' <param name="DataItem"> 
''' The data item to associate with the <see cref="RepeaterItem"></see>. 
''' Ignored if <paramref name="DataBind"></paramref> is False. 
''' </param> 
''' 
''' <returns>The new <see cref="System.Web.UI.WebControls.RepeaterItem"></see>.</returns> 
''' 
''' <remarks></remarks> 
''' 
''' <revisionhistory> 
''' 100907 MEH Created from reflection on the private Repeater.CreateItem, with no changes. 
''' </revisionhistory> 
'''--------------------------------------------------------------------- 
Private Overloads Function CreateItem(ByVal ItemIndex As Integer, ByVal ItemType As ListItemType, ByVal DataBind As Boolean, ByVal DataItem As Object) As RepeaterItem 
<snip> 

'''--------------------------------------------------------------------- 
''' Property: FooterTemplate 
''' 
''' <summary> 
''' Gets or sets the <see cref="System.Web.UI.ITemplate" /> that 
''' defines how the footer section of the <see cref="ExtensibleRepeater" /> 
''' control is displayed. 
''' </summary> 
''' 
''' <value> 
''' A <see cref="System.Web.UI.ITemplate" /> that defines how the 
''' footer section of the <see cref="ExtensibleRepeater" /> control is 
''' displayed. 
''' The default value is Nothing. 
''' </value> 
''' 
''' <remarks> 
''' This property does not change the inherited behaviour. It is 
''' only overridden to highlight this missing feature: 
''' TODO: BUG: This will appear before an additional item if one is added. 
''' </remarks> 
''' 
''' <revisionhistory> 
''' 100907 MEH Created. 
''' </revisionhistory> 
'''--------------------------------------------------------------------- 
<Obsolete("BUG: This will appear before an additional item if one is added.")> _ 
<Description("The template used for the footer. BUG: This will appear before an additional item if one is added."), _ 
Browsable(False), DefaultValue(CStr(Nothing)), _ 
PersistenceMode(PersistenceMode.InnerProperty), _ 
TemplateContainer(GetType(RepeaterItem))> _ 
Public Overrides Property FooterTemplate() As ITemplate 
<snip> 

'''--------------------------------------------------------------------- 
''' Sub: DataBind 
''' 
''' <summary> 
''' Binds the <see cref="ExtensibleRepeater"></see> control and all 
''' its child controls to the specified data source. 
''' </summary> 
''' 
''' <remarks> 
''' <see cref="AddNew"></see> must be called again to restore the 
''' additional item if it is needed. 
''' </remarks> 
''' 
''' <revisionhistory> 
''' 100908 MEH Created. 
''' </revisionhistory> 
'''--------------------------------------------------------------------- 
Overrides Sub DataBind() 
    additionalItem = Nothing 
<snip> 

End Class