Gridview Linkbutton Code behind - asp.net

Question

Until now, I was working with VS 2003 and recently migrated to VS 2008. I am facing some peculiar problems.
In Vs 2003,I had a Datagrid, and one of the field was ButtonField(Link button). It was not a template field. The user clicks on the field and some data gets generated.
I have written a code, in Vb, like this, on dg_ItemCommand:
Strid = Ctype(e.commandsource,linkbutton).text
Now i want to use same method,for the gridview (I think datagrid is gridview in 2008). I wrote a code like this on dg_Rowcomand
Private Sub dgSampleCustomer_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles dgSampleCustomer.RowCommand
Try
Dim strid As String
Dim i As Integer
strid = CType(e.CommandSource, LinkButton).Text
...
It is throwing a error.
Unable to cast object of type 'System.Web.UI.WebControls.GridView' to
type 'System.Web.UI.WebControls.ButtonField'.
Can anybody help me out!

Answer 1

It looks like the source of the command is the GridView itself, not the button you are clicking. What you probably want to do is set this value you are looking for in the "CommandArgument" property of the Linkbutton. The markup would look something like this:
<asp:LinkButton ID="myLinkButton" runat="server"
CommandName="MyCommandName"
CommandArgument="MySpecialValue"
Text="Click Me" />
Then in the event you would simply:
' strid = "MySpecialValue"
strid = e.CommandArgument.ToString()
Instead of pulling the ID from the name of the control, you can now easily get it from the command. CommandName is optional in this particular case, but comes in handy if you have multiple buttons on a grid that do different things, such as "Edit" and "Delete". Then you can use the command name to handle each command in their own way in the same event:
If (e.CommandName = "Edit") Then
' Do Some Edit Code
End If

Answer 2

I'm wondering why you are trying to cast the command source to a LinkButton? If you would like to attach or otherwise send some kind of row-specific information to your button handler, you are able to do this with the CommandName and CommandArgument attributes of the ButtonField.
Like:
<asp:Gridview ID="...">
...
<columns>
<asp:buttonfield buttontype="Link"
commandname="Generate"
text="Generate"/>
...
</columns>
</asp:GridView>
This will be retrievable in the event handler by using:
if(e.CommandName=="Generate")
{
// Convert the row index stored in the CommandArgument
// property to an Integer.
string rowIndex = Convert.ToInt32(e.CommandArgument);
...
}
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.rowcommand.aspx
UPDATE: (use DataKeys)
Since e.CommandArgument returns a row index, and you want the ID, use the DataKeys collection, first add your ID column to the DataKeyNames collection...
<asp:GridView ... DataKeyNames="ID">
... and then retrieve the values from the DataKeys collection, like:
GridView sourceGridView = (GridView) e.CommandSource;
rowIndex = Convert.ToInt32(e.CommandArgument);
strID = sourceGridView.DataKeys[rowIndex]["ID"];

Answer 3

You can try this in your rowcommand event
Dim index = Convert.ToInt32(e.CommandArgument)
Dim row = dg.Rows(index)
'find your linkbutton in template field (replace "lnkBtn" with your's)
Dim myLinkButton = CType(row.FindControl("lnkBtn"), LinkButton)
Dim strid As String = myLinkButton.Text
Let me know if it helps.