Add total in VB.Net Gridview - asp.net

Question

I can not manage to get the gridview display the total in a footer
I've tried the following:
<asp:GridView ID="GV" runat="server"
DataSourceID="SqlQuery" EmptyDataText="No data">
<Columns>
<asp:BoundField DataField="Weekday" FooterText=" " HeaderText="Weekday" />
<asp:BoundField DataField="Volume" DataFormatString="{0:N0}"
FooterText="." HeaderText="Volume" />
</Columns>
</asp:GridView>
Protected Sub GV_rowdatabound(sender As Object, e As GridViewRowEventArgs) Handles GV.RowDataBound
Dim Volume as integer = 0
For Each r As GridViewRow In GV.Rows
If r.RowType = DataControlRowType.DataRow Then
Volume = Volume + CDec(r.Cells(1).Text)
End If
Next
GV.FooterRow.Cells(1).Text = Math.Round(Volume , 0)
End Sub
This gives me an error messages:
Object reference not set to an instance of an object
I followed advice in the following page and I changed the code:
trying to total gridview in asp
Sub GV_WeekSumary_rowcreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
Dim Volume as integer = 0
For Each r As GridViewRow In GV.Rows
If r.RowType = DataControlRowType.DataRow Then
Volume = Volume + CDec(r.Cells(1).Text)
End If
Next
If e.Row.RowType = DataControlRowType.Footer Then
e.Row.Cells(1).Text = Math.Round(Volume , 0)
End If
End Sub
This does not give an error, but the footer does not show any value.
I've tried also the following:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim Volume as integer = 0
For Each r As GridViewRow In GV.Rows
If r.RowType = DataControlRowType.DataRow Then
Volume = Volume + CDec(r.Cells(1).Text)
End If
Next
GV.FooterRow.Cells(1).Text = Math.Round(Volume, 0)
GV.DataBind()
End Sub
Still no value in the footer, but when I debbug it I can see that footer is assisgned the value I need. Why it is not displayed in the website?
Any idea how I can get this to work?

Answer 1

You must use DataBound event.
Try this:
Protected Sub GV_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles GV.DataBound
Dim Volume As Decimal = 0
For Each r As GridViewRow In GV.Rows
If r.RowType = DataControlRowType.DataRow Then
Volume += Convert.ToDecimal(r.Cells(1).Text)
End If
Next
GV.FooterRow.Cells(1).Text = Math.Round(Volume, 0).ToString()
End Sub