[英]GridView loses data on postbacks when using DataPager
我有一個CustomGridView(擴展GridView)和一個DataPager,它們在.net 3.5中都可以正常工作,但在.net 4中卻不能。問題是,當在除第一個頁面之外的其他頁面上發生回發時,網格的viewstate丟失了。 這是一個很大的項目,並且由於每次更新的代碼太多(我們開始了,但我們只創建了更多的錯誤),因此不允許在每次回發中進行數據綁定。
我已經測試了內置的DataPager Webcontrol,並且取得了相同的結果。 我們知道我們應該為網格使用內置的尋呼機,但是該解決方案是不可能的,因為它要更新的代碼太多。
使用CustomGridView的所有頁面和gridpage 1上都會出現問題,一切正常
這是一個已知問題,是否有解決方法?
我從一個簡單的項目中給您提供代碼,但發生相同的問題(在.net 3.5中工作,但在.net 4中工作):
WebForm1.aspx:
<cc1:SimpleCustomGridView ID="CustomGridView1" runat="server"
AutoGenerateColumns="false" PageSize="4" AllowPaging="true"
onpageindexchanging="CustomGridView1_PageIndexChanging"
onrowcommand="CustomGridView1_RowCommand" EnableViewState="true" ViewStateMode="Enabled" Visible="true">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="lnkButton" runat="server" Text='<%#Eval("Name") %>' CommandName="lnkClick" CommandArgument='<%#Eval("Id") %>'></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</cc1:SimpleCustomGridView>
<br />
<uc:DataPager ID="DataPager" runat="server" CustomGridViewID="CustomGridView1" />
WebForm1.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DataBind(0);
}
}
private void DataBind(int pageIndex)
{
int rowIndex = pageIndex * CustomGridView1.PageSize;
int pageSize = CustomGridView1.PageSize;
int total;
List<DataContainer> list = DataContainer.GetData(rowIndex, pageSize, out total);
CustomGridView1.RowCount = total;
CustomGridView1.DataSource = list;
CustomGridView1.DataBind();
}
protected void CustomGridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
if (e.NewPageIndex > -1)
{
CustomGridView1.PageIndex = e.NewPageIndex;
DataBind(e.NewPageIndex);
}
}
protected void CustomGridView1_RowCommand(object sender, GridViewCommandEventArgs e) { }
SimpleCustomGridView.cs:
public class SimpleCustomGridView : GridView
{
public override int PageIndex
{
get
{
if (ViewState[this.ClientID + "PAGEINDEX"] == null)
ViewState[this.ClientID + "PAGEINDEX"] = 0;
return (int)ViewState[this.ClientID + "PAGEINDEX"];
}
set
{
base.PageIndex = value;
ViewState[this.ClientID + "PAGEINDEX"] = value;
}
}
public int RowCount
{
set
{
HttpContext.Current.Session[this.ClientID + "TOTALPAGECOUNT"] = value;
}
get
{
return HttpContext.Current.Session[this.ClientID + "TOTALPAGECOUNT"] == null ? 0 :
Convert.ToInt32(HttpContext.Current.Session[this.ClientID + "TOTALPAGECOUNT"]);
}
}
public void GotoPage(int pageIndex)
{
GridViewPageEventArgs args = new GridViewPageEventArgs(pageIndex);
OnPageIndexChanging(args);
}
}
CustomGridViewpager.ascx.cs:
public partial class CustomGridViewpager : UserControl
{
public string CustomGridViewID { get; set; }
private SimpleCustomGridView _gridView;
protected override void OnInit(EventArgs e)
{
base.OnInit(e);
_gridView = (SimpleCustomGridView)Parent.FindControl(CustomGridViewID);
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
int totalRows = _gridView.RowCount;
int pageIndex = _gridView.PageIndex;
int pageSize = _gridView.PageSize;
int totalPages = (int)Math.Ceiling(totalRows / (double)pageSize);
StringBuilder sb = new StringBuilder();
sb.Append(pageIndex + 1);
sb.Append("/");
sb.Append(totalPages);
PageIndexLabel.Text = sb.ToString();
PrevPageButton.Visible = pageIndex > 0;
NextPageButton.Visible = pageIndex < totalPages - 1;
}
protected void NextPageButton_Click(object sender, EventArgs e)
{
_gridView.GotoPage(_gridView.PageIndex + 1);
}
protected void PrevPageButton_Click(object sender, EventArgs e)
{
_gridView.GotoPage(_gridView.PageIndex - 1);
}
}
嘗試放入DataBind(0);
在webform的OnPreRender()
方法中
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
DataBind(0);
}
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