Whats wrong wiht this code? Invalid cast

[MrNorth]

Dim chkBox As New CheckBox
        Dim oOrder As New COrder
        For Each di As DataGridItem In dgOrders.Items
            chkBox = CType(di.Cells(4).Controls(0), CheckBox)
            If chkBox.Checked Then
                oOrder.CloseOrder(di.Cells(0).Text)
            End If
        Next

This code occurs when I hit a save button and it checks which checkboxes in the grid that was checked and update the db (oorder.closeorder)

but the line

chkBox = CType(di.Cells(4).Controls(0), CheckBox)

doesn't work, I get an invalid cast exception... why? is there any other way to do it?

kind regards
henrik

[Edneeis]

Make sure Control(0) is in fact a checkbox. Try:
Msgbox(TypeName(di.Cells(4).Controls(0)))

[MrNorth]

Hm ok this is wierd. In my datagrid I have:

Buttoncolumn, bound control, boundcontrol, templatecontrol, templatecontrol


When I check

di.Cells(0).Controls(0) I get linkbutton, which is great

di.Cells(1).Controls(0) <--invalid index (no control here)

di.Cells(2).Controls(0) <--invalid index (no control here)

di.Cells(3).Controls(0) <--LITERAL Control (wierd, because it's checkbox)

di.Cells(4).Controls(0) <--LITERAL Control (wierd, because it's checkbox)


I really have no clue why it is like this....?


kind regards
Henrik

[nemaroller]

IF I know exactly what control belongs there..
I use:

Dim X as Checkbox = DirectCast(di.Cells(4).Controls(0),CheckBox)

I think your problem lies in the fact, that the datagrid has temporarily placed a literal where the checkbox will take it place (before the page has rendered)or before the data has been binded. Once the binding actually occurs, the datagrid probably renders a checkbox in there.

You see, you need to put your code in the databinding event, or shortly after in the prerender.

[MrNorth]

Well the page works like this:

First I render a few textboxes and a search button

The user click search and I perform a databind on the datagrid if I got any values back from the db. I also make a button "save" visible, and it is in that button event that I want to loop through the datagrid and check if any checkboxes are checked... Here is the code

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Not Page.IsPostBack Then
            FillUI()
        End If
    End Sub
 
    Public Sub FillUI()
        Dim oCompany As New clsCompany
        Dim oStatus As New clsStatus
        With ddlSalesCompany
            .DataSource = oCompany.GetNamesDr
            .DataValueField = "COMPANY_KEY_NO"
            .DataTextField = "NAME"
            .DataBind()
            .SelectedItem.Text = "*"
            oCompany = Nothing
        End With
 
 
 
    End Sub
 
    Private Sub btnSearchInvoice_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearchInvoice.Click
        Dim oOrder As New COrder
        dgOrders.DataSource = oOrder.GetOrders(txtOrderNo.Text, ddlSalesCompany.SelectedItem.Text, ddlStatus.SelectedItem.Text)
        dgOrders.DataBind()
        If dgOrders.Items.Count < 1 Then
            dgOrders.Visible = False
            btnSaveOrder.Visible = False
        Else
            dgOrders.Visible = True
            btnSaveOrder.Visible = True
        End If
 
    End Sub
 
 
 
    Public Sub SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs)
        Dim lb As New LinkButton
        lb = CType(e.Item.Cells(0).Controls(0), LinkButton)
        Server.Transfer("AInvoiceDetails.aspx" & "?OrderId=" & lb.Text)
        'Response.Write("Text" & lb.Text)
    End Sub
 
 
 
    Private Sub btnSaveOrder_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveOrder.Click
        'Here I want to make something nice for each checkbox that is checked
 
    End Sub

Im really not sure what you mean... the data is bound to the grid... and the savebutton doesn't perform a postback?? Because when I click the button the data is still bound to the grid!

anyone with an explanation???

kind regards
Henrik

[nemaroller]

Your save button must be posting back, because unless you wrote JScript, (and the fact that you have Private Sub btnSaveOrder_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveOrder.Click
in your code means your handling it on a postback.)

What I was getting at was the Checkboxes may not exist inside your datagrid at the time you are checking (the SaveOrder_Click function), because the DataGrid hasn't rendered yet.

Try putting this in the Page_Init event (it may solve it), or it may not:
EnsureChildControls()

[nemaroller]

Otherwise try this code in your savebutton-click event (grabbed from mspress Programming VB.NET):

Dim dg as DataGridItem
For Each dg In dgrCompanies.Items 'find the checkbox in the row
Dim cb As CheckBox = DirectCast(dg.FindControl ( "chkSelect"),CheckBox) 'replace chkSelect with name of your checkbox
   'if checked
   IF cb.Checked Then
    'do something
   End if
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