Datagrid中的复选框保留VB.NET中回发时的检查值，但不保留C＃

Question

Hey there, I have a project in VB.NET which is working fine which essentially has a Datagrid that has a TemplateColumn included which is a column of Checkboxes. The code to declare the datagrid is here...

<asp:datagrid id="dgDates" OnItemCommand="gridEventHandler" BorderColor="Black" BorderWidth="1px"
CellPadding="3" runat="server" AutoGenerateColumns="False" HorizontalAlign="Left" AllowSorting="True"
OnSortCommand="SortData" OnItemDataBound="gridItemDataBound">
<HeaderStyle Font-Underline="True" Font-Bold="True" HorizontalAlign="Center" ForeColor="Black"
    BackColor="#D4D0C8"></HeaderStyle>
<Columns>
    <asp:BoundColumn DataField="strParameterName" SortExpression="strParameterName" HeaderText="Parameter Name"></asp:BoundColumn>
    <asp:BoundColumn DataField="dtParameterValue" SortExpression="dtParameterValue" HeaderText="Parameter Value"></asp:BoundColumn>
    <asp:TemplateColumn HeaderText="Constant" SortExpression="blnStatic" ItemStyle-HorizontalAlign="Center">
        <ItemTemplate>
            <asp:CheckBox ID="cbStaticRolling" Checked="False" Runat="server" AutoPostBack="true"></asp:CheckBox>
        </ItemTemplate>
    </asp:TemplateColumn>
</Columns>

as you can see the Checkbox has Autopostback="true" but there are other things on the page which produce postbacks as well.

My Page_load has this in it, being called on every load of the page, postbacks included...

Dim strGUID As String
strGUID = Session("strGUID")
dgDates.DataSource = SqlHelper.ExecuteDataset(ConfigurationManager.AppSettings(Web.  [Global].CfgKeyConnStringADMIN), "dbo.spRptGetSchedulingDates", strGUID)
dgDates.DataBind()
intNumberOfDates = dgDates.Items().Count

as well my code behind has the following code for the gridItemDataBound

Protected Sub gridItemDataBound(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs)
    'hide the intRptSchedulingDatesID for each row in the checkbox's content style variable
    If (e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem) Then
        CType(e.Item.FindControl("cbStaticRolling"), CheckBox).Style("Content") = CType(e.Item.DataItem, System.Data.DataRowView).Item("intRptSchedulingDatesID")
    End If
End Sub

everything you see sbove is working perfectly fine...in the sense that when I click one of the checkboxes, the page_load fires, the gridItemDataBound fires on DataBind() and when all is done, the checkbox retains the value that the user clicked the checkbox.

With all this exact same code converted to C#....the events all fire in the same order, but the checkbox selected value always clears...any thoughts??

Answer 1

I'd say the problem is that you're are binding the grid on every postback (I can't explain the difference between VB and C#). This clears your selections. Why are you doing this?

Answer 2

You bind the grid on every page_load, this causes checkbox to be always the same.

Try to attach a checkedchange event on ItemDataBound and when event fires, store checkbox value on a session variable.

On ItemDataBound, check session variable and if its null, run this code, otherwise read checkbox's value from your session variable

And On Page_Load, if not IsPostBack (page is loading first time), set your session value to null