Asp.net C# listview 分页加载视图状态失败

Question

在列表视图中使用 Datapager 进行分页时遇到了一些问题。 页面非常简单。输入搜索文本。点击搜索按钮。将结果显示到列表视图。结果显示正常，但每次单击页码时都会出现以下错误：

Server Error in '/' Application.

Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[HttpException (0x80004005): Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.]
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +317
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +144
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +204
   System.Web.UI.Page.LoadAllState() +464
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1849

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34212 

---

这是我的妆：

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Search.aspx.cs" Inherits="ITDB.Views.Employee.Search"%>
<asp:Content ID="Content1" ContentPlaceHolderID="Header" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    <br />
    <asp:TextBox ID="SearchText" runat="server"></asp:TextBox>
    <asp:Button ID="cmdSearch" runat="server" Text="Search" OnClick="cmdSearch_Click" />
    <hr />

    <asp:ListView id="SearchList" runat="server"
            DataKeyNames="EmployeeID" 
            ItemType="ITDB.DBContext.Employee"      
            >
            <EmptyDataTemplate>
                There are no entries found for Employee
            </EmptyDataTemplate>
            <LayoutTemplate>                                                       
                <asp:PlaceHolder runat="server" id="itemPlaceholder" />
               <asp:DataPager PageSize="5"  runat="server">
                    <Fields>
                        <asp:NextPreviousPagerField ShowLastPageButton="False" ShowNextPageButton="False" ButtonType="Button" ButtonCssClass="btn" />
                        <asp:NumericPagerField ButtonType="Button"  NumericButtonCssClass="btn" CurrentPageLabelCssClass="btn disabled" NextPreviousButtonCssClass="btn" />
                        <asp:NextPreviousPagerField ShowFirstPageButton="False" ShowPreviousPageButton="False" ButtonType="Button" ButtonCssClass="btn" />
                    </Fields>
                </asp:DataPager>                
            </LayoutTemplate>
            <ItemTemplate>
                <%#: Item.FirstName + " " + Item.LastName%>
                <br />   
            </ItemTemplate>
    </asp:ListView>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="AfterForm" runat="server">
</asp:Content>

---

后面的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.Entity;
using ITDB.DBContext;

namespace ITDB.Views.Employee
{
    public partial class Search : System.Web.UI.Page
    {
        protected ITDB.DBContext.ITDB_MSSQL_Connection _db = new ITDB.DBContext.ITDB_MSSQL_Connection();

        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void cmdSearch_Click(object sender, EventArgs e)
        {
            String szSearch = SearchText.Text;
            SearchList.DataSource = GetSearchList(szSearch);
            SearchList.DataBind();
        }

        private List<ITDB.DBContext.Employee> GetSearchList(String searchString)
        {
            return (from employee in _db.Employee
                    where employee.FirstName.Contains(searchString) ||
                          employee.LastName.Contains(searchString)
                    orderby employee.LastName
                    select employee
                        ).ToList();
        }

    }
}

我在这里做错了什么？ 非常感谢您的帮助。

Answer 1

这里有一个很好的答案，因为这些字段直到运行时才知道。

http://blog.yeshere.org/2011/04/using-datapager-in-listview.html

将您的 DataPager 的 ID 设置为：DataPager1

您应该添加并实现 ListView 的 PagePropertiesChanging 事件。事件参数中的 PagePropertiesChangingEventArgs 将提供所有需要的分页属性（StartRowIndex 和 MaximumRows），以便您可以将它们提供给 DataPager。

如果 DataPager 被放置在 ListView 中，像你这样：

protected void ListView1_PagePropertiesChanging(object sender, PagePropertiesChangingEventArgs e) {
  ListView lv = sender as ListView;
  DataPager pager = lv.FindControl("DataPager1") as DataPager;
  pager.SetPageProperties(e.StartRowIndex, e.MaximumRows, false);
  BindData();  // set DataSource to ListView and call DataBind() of ListView
}

如果在外面：

protected void ListView1_PagePropertiesChanging(object sender, PagePropertiesChangingEventArgs e) {     
      this.DataPage1.SetPageProperties(e.StartRowIndex, e.MaximumRows, false);
      BindData();  // set DataSource to ListView and call DataBind() of ListView
    }