PagedDataSource在后续页面中没有显示数据

Question

它可能很小，但我还没有弄清楚为什么以下不能完全工作。用户第一次提交搜索时，搜索结果的第一页正确显示。但是，当用户尝试使用“上一页”和“下一页”按钮进行导航时，中继器不会显示来自DataTable的适当数据。

search.aspx

<asp:Repeater ID="rptSearchResults" runat="server" OnItemDataBound="rptSearchResults_ItemDataBound"> 
    <ItemTemplate> 
     <div> 
      <asp:Literal ID="ltlCustName" runat="server" /> 
     </div> 
    </ItemTemplate> 
</asp:Repeater> 

search.aspx.vb

Public dtCustomers As DataTable = New DataTable() 
Sub Page_Load(ByVal Sender As Object, ByVal E As EventArgs) Handles Me.Load 
    ' Check to see if this is the first time postback-ing to itself. 
    blnFirstPostBack = (Request.Form("firstpb") = "1") 

    ' When the page first loads, show the search form with search options. 
    If Not Page.IsPostBack Then 
     Session("StoredDT") = Nothing 
     ShowSearchForm() 
    ' Once the form is submitted, show the search results. 
    Else 
     Response.Write("DEBUG: Get Data") 
     If blnFirstPostBack Then 
      GatherFormData() 
      dtCustomers = BuildDT() 
      Session("StoredDT") = dtCustomers 
      BindData() 
     ElseIf Not Session("StoredDT") Is Nothing Then 
      dtCustomers = Session("StoredDT") 
     End If 
    End If 
End Sub 

Sub BindData() 
    Response.Write("DEBUG: Bind Data") 
    ' At this point, I've checked that the dtCustomers is showing the proper data (e.g., grabbing from session when appropriate). 
    Dim objPDS As PagedDataSource = New PagedDataSource() 
    objPDS.DataSource = dtCustomers.DefaultView 
    objPDS.AllowPaging = True 
    objPDS.PageSize = intNumPerPage 
    ' I've checked that Me.ViewState("_CurrentPage") gets updated to the correct page. 
    objPDS.CurrentPageIndex = Me.ViewState("_CurrentPage") 
    rptSearchResults.DataSource = objPDS 
    ' I'm not sure if the error is here but although the dtCustomers is the proper data, the PagedDataSource and the binding here doesn't seem to play nice. 
    Call rptSearchResults.DataBind() 
End Sub 

' Subroutine called when the previous page button is pressed. 
Sub GoToPrevPage() 
    Response.Write("DEBUG: Prev Page") 
    ' Set viewstate variable to the previous page. 
    Me.ViewState("_CurrentPage") -= 1 
    BindData() 
End Sub 

' Subroutine called when the next page button is pressed. 
Sub GoToNextPage() 
    Response.Write("DEBUG: Next Page") 
    ' Set viewstate variable to the next page. 
    Me.ViewState("_CurrentPage") += 1 
    BindData() 
End Sub 

Protected Sub rptSearchResults_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles rptSearchResults.ItemDataBound 
    Dim item As RepeaterItem = e.Item 
    Dim strCustName As String = "" 
    If (item.ItemType = ListItemType.Item) Or (item.ItemType = ListItemType.AlternatingItem) Then 
     strCustName = e.Item.DataItem("CustName") 
     Dim ltlCustName As Literal = CType(e.Item.FindControl("ltlCustName"), Literal) 
     ltlCustName.Text = strCustName 
    End If 
End Sub 

示例页面1（示出了适当的数据）：

DEBUG: Get Data 
DEBUG: Bind Data 
Laurence Clinton 
John Doe 
Sean King 
Jane Smith 

示例页面2（不显示正确的数据但显示缺少数据的足够空间）：

DEBUG: Get Data 
DEBUG: Next Page 
DEBUG: Bind Data 
[no name showing here 5] 
[no name showing here 6] 
[no name showing here 7] 
[no name showing here 8] 

请原谅这个缩写代码，但实际的代码很大，所以简化就是让它更容易理解问题的核心。

让我知道是否有任何不清楚或是否需要更多代码。提前致谢！

更新2013年2月19日：

因此与代码摆弄了一下后，我想在中继子程序中出现错误。现在，中继器内部的原始字面值正在工作。出于某种原因，我不认为它的工作，但它现在正常工作。问题是当我们在中继器子程序内部使用自定义控件时更进一步。看来这些信息并没有传递到控制中。控件被正确调用，因为只有在控件中找到的支持HTML才能正确输出，但我们试图传入控件的客户信息不会进入内部。下面是修改后的代码：

search.aspx

<asp:Repeater ID="rptSearchResults" runat="server" OnItemDataBound="rptSearchResults_ItemDataBound"> 
    <ItemTemplate> 
     <div> 
      <asp:Literal ID="ltlCustName" runat="server" /> 
      <Acme:CustInfo ID="AcmeCustInfo" runat="server" /> 
     </div> 
    </ItemTemplate> 
</asp:Repeater> 

search.aspx.vb

Protected Sub rptSearchResults_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles rptSearchResults.ItemDataBound 
    Dim item As RepeaterItem = e.Item 
    Dim strCustName As String = "" 
    If (item.ItemType = ListItemType.Item) Or (item.ItemType = ListItemType.AlternatingItem) Then 
     strCustName = e.Item.DataItem("CustName") 

     ' This literal properly shows the customer name on subsequent pages so the customer name reaches this point properly. 
     Dim ltlCustName As Literal = CType(e.Item.FindControl("ltlCustName"), Literal) 
     ltlCustName.Text = strCustName 

     ' This control gets called properly but strCustName doesn't 
     ' get passed into the control. The control works fine for the 
     ' first page but subsequent pages do not work. Also, the 
     ' control works fine when PagedDataSource is not used. 
     Dim AcmeCustInfo As CustInfo = CType(e.Item.FindControl("AcmeCustInfo"), CustInfo) 
     AcmeCustInfo.CustName = strCustName 
    End If 
End Sub 

每请求从安

这里是CustInfo的代码。毋庸置疑，很多绒毛已经被剥离出来专注于这个问题，但如果缺少任何有用的东西，请让我知道，我会相应地更新示例。

custinfo.ascx

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="CustInfo.ascx.vb" Inherits="CustInfo" %> 

<div style="border: 1px solid black;"> 
    <asp:Literal ID="ltlCustName" runat="server" /> 
</div> 

custinfo.ascx.vb

Imports System 
Imports System.Web 
Imports System.Web.Security 
Imports System.Web.UI 
Imports System.Web.UI.WebControls 
Imports System.Web.UI.HtmlControls 
Imports System.Configuration 
Imports System.Data 
Imports System.Data.SqlClient 
Imports System.IO 
Imports System.Web.HttpUtility 

Partial Class CustInfo 
    Inherits System.Web.UI.UserControl 

    Private _CustName As String = "" 

    Public Property CustName() As String 
     Get 
      Return _CustName 
     End Get 
     Set(value As String) 
      _CustName = value 
     End Set 
    End Property 

    Public Sub Page_Load(ByVal Sender As Object, ByVal E As EventArgs) Handles Me.Load 
     Dim ltlCustName As Literal = CType(FindControl("ltlCustName"), Literal) 
     ltlCustName.Text = "<b>Name: " & CustName & "</b>" 
    End Sub 
End Class 

Answer 1

我不是一个PagedDataSource专家，但我已经使用的用户控件广泛。

您在Load子例程中设置CustInfo控件中的文字值。如果我没有弄错，那么在CustInfo控件创建时会被调用。在调用OnItemDataBound之前会发生这种情况，所以 - 我认为 - 在您分配CustName属性的值之前，将会发生Load子例程并将文本的值设置为空字符串。要解决此问题，请稍后尝试设置文字的值，例如在PreRender子例程中。

它看起来像你在每一个回传结合，所以下面的不应该是一个问题，但如果你不是，这里有一些事情可能会影响您：

1. ItemDataBound只运行如果你重新绑定。如果您的中继器已启用ViewState，则将在回发时重新创建控件，并且ItemCreated将运行，但ItemDataBound不会。所以你永远不会重新设置你的CustName属性。这可能是因为...
2. ...您的CustName属性有一个变量作为后备存储：它不保存在ViewState中。因此，当用户控件重新创建时，您之前设置的CustName属性将不再存在：您的文字内容将被设置为属性为CustName属性的默认值的空字符串。

这两者合起来会给出你描述的行为。但是，因为它看起来像你绑定每一个回传（最终），可能不是问题。我包括它的完整性。