How can i add a row to a data-bound gridview without causing viewstate errors?
I'm trying to add a row grouping row to my data-bound gridview. It works fine on the first response, but at the postback i got the "Failed to load viewstate" error.
There is the code for the GridView's RowDataBound event:
Private Sub AddGroupingRow(ByRef eRow As GridViewRow, ByVal Css As String, ByVal ColSpan As Integer, ByVal Txt As String)
Dim cell As New TableCell()
cell.ColumnSpan = ColSpan
cell.CssClass = "Spacing FieldCell"
cell.Text = Txt
Dim row As New GridViewRow(-1, -1, DataControlRowType.DataRow, DataControlRowState.Normal)
row.CssClass = Css
row.Cells.Add(cell)
Dim tbl As Table
tbl = eRow.Parent
tbl.Rows.AddAt(eRow.RowIndex + 1, row)
End Sub
Private Prev_Client_ID As Integer = -1
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
Dim dr As Data.DataRowView = TryCast(e.Row.DataItem, Data.DataRowView)
If dr IsNot Nothing AndAlso d开发者_高级运维r.Row.RowState <> Data.DataRowState.Added Then
Dim Client_ID As Integer = dr.Item("Client_ID")
If Client_ID <> Prev_Client_ID Then AddGroupingRow(e.Row, "Group", 8, dr.Item("Client_Name"))
Prev_Client_ID = Client_ID
End If
End If
End Sub
I know that it's easier to create the grouping rows at the datasource, but deriving from this code, i want to create some base to other grids at the site.
Try this link. it should help you. I too had the same problem. The only way to resolve is a proper understanding of viewstate.
After some thinking, the answer could not be simpler: disable the viewstate of the gridview.
I was re-binding the datasource at every paging or sorting, so the need for the viewstate was minimum, except for the PageSize and PageIndex, that i became forced to keep track manually.
This is a considerable trade-off: things like PageSize and PageIndex must be managed manually afterwards, since their state are keeped by the ViewState.
So, even doing exactly what i was meant to do, i've decided to adopt an simple alternative solution:
If Cliente_ID <> Cliente_ID_Anterior Then
For i As Integer = 0 To e.Row.Cells.Count - 1
e.Row.Cells(i).Style("border-top") = "solid 1px #777777"
Next
e.Row.Cells(0).Style("border-bottom") = "none"
Else
e.Row.Cells(0).Text = " "
e.Row.Cells(0).Style("border-top") = "none"
e.Row.Cells(0).Style("border-bottom") = "none"
End If
It still groups the column, but in another way, and is more sort friendly. I could use rowspans and turn cells invisible, but it would be harder to keep. Besides, I'll need to paint the line when the user moves the mouse over it, and a rowspan would hinder a lot.
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