DropDownList is not posting back - asp.net

Question

I'm using Visual Studio 2005 and ASP. NET 2.0 with this program. This is written in VB.net
Right now, we've got a Gridview that is embedded and databound into another gridview. The 2nd Gridview is hidden by default and expanded by the user. Within the 2nd gridview are several DropDownLists. The problem is that these DropDownLists are not firing the OnSelectedIndexChanged functon nor AutoPostback whenever I change the selecteditem.
I'm curious as to why it is not firing. Thank you.
Gridview1:
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
Dim row As GridViewRow = e.Row
Dim strSort As String = String.Empty
Dim strCNRNum As String
' Make sure we aren't in header/footer rows
If row.DataItem Is Nothing Then
Return
End If
' Find Child GridView control
Dim gv As GridView = New GridView()
gv = row.FindControl("GridView2")
If gv.UniqueID = gvUniqueID Then
gv.EditIndex = gvEditIndex
ClientScript.RegisterStartupScript(GetType(Page), "Expand", "<SCRIPT LANGUAGE='javascript'>expandcollapse('div" + e.Row.DataItem("CNR_NUM").ToString() & "','one');</script>")
End If
' Prepare the query for Child GridView by passing
' the Customer ID of the parent row
'Dim dsTemp As SqlDataSource
'dsTemp = ChildDataSource(e.Row.DataItem("CNR_NUM").ToString, strSort)
'gv.DataSource = dsTemp
'gv.DataBind()
strCNRNum = e.Row.DataItem("CNR_NUM").ToString()
Dim dt As DataTable = New DataTable()
Dim con As SqlConnection = New SqlConnection(ConnectionString)
Try
con.Open()
Dim strSQL As String
strSQL = "select " & _
"CS.SID, " & _
"CS.CNR_NUM, " & _
"CS.STEP_NUM, " & _
"CS.SERVER_ID, " & _
"S.SERVER_NM, " & _
"CS.DATABASE_ID, " & _
"D.DATABASE_NM, " & _
"CS.CMD_FILE_NM, " & _
"CS.EXECUTE_DTTM, " & _
"CS.STEP_TYPE_ID, " & _
"ST.STEP_TYPE, " & _
"ISNULL(CS.LOG_FILE_NM,'') as LOG_FILE_NM " & _
"from " & _
"dbo.CNR_STEPS CS INNER JOIN dbo.CNR_SERVERS S on CS.SERVER_ID = S.SERVER_ID " & _
"INNER JOIN dbo.CNR_DATABASES D ON CS.DATABASE_ID = D.DATABASE_ID " & _
"INNER JOIN dbo.CNR_STEP_TYPES ST ON CS.STEP_TYPE_ID = ST.STEP_TYPE_ID " & _
"where " & _
"CS.CNR_NUM = '" & strCNRNum & "' " & _
"order by " & _
"CS.STEP_NUM"
Dim cmd As SqlCommand = New SqlCommand(strSQL, con)
Dim da As SqlDataAdapter = New SqlDataAdapter(cmd)
da.Fill(dt)
If dt.Rows.Count > 0 Then
gv.DataSource = dt
gv.DataBind()
Else
dt.Rows.Add(dt.NewRow())
dt.Rows(0)("CNR_NUM") = strCNRNum
dt.Rows(0)("LOG_FILE_NM") = ""
gv.DataSource = dt
gv.DataBind()
Dim colCount As Integer = gv.Columns.Count
gv.Rows(0).Cells.Clear()
gv.Rows(0).Cells.Add(New TableCell())
gv.Rows(0).Cells(0).ColumnSpan = colCount
gv.Rows(0).Cells(0).HorizontalAlign = HorizontalAlign.Center
gv.Rows(0).Cells(0).ForeColor = System.Drawing.Color.Red
gv.Rows(0).Cells(0).Font.Bold = True
gv.Rows(0).Cells(0).Text = "No Steps Defined"
End If
Catch ex As Exception
lblMessage.ForeColor = Drawing.Color.Red
lblMessage.Text = "Error: " & ex.Message.ToString()
'ClientScript.RegisterStartupScript(GetType(Page), "Message", "<SCRIPT LANGUAGE='javascript'>alert('" + ex.Message.ToString().Replace("'", "") + "');</script>")
End Try
End Sub
ASP code for the 2nd gridview, which is within the first one:
<asp:GridView ID="GridView2" AllowPaging="True" AllowSorting="true" Width="100%" Font-Size="Small" AutoGenerateColumns="false" runat="server" DataKeyNames="CNR_NUM" ShowFooter="true" OnRowEditing = "GridView2_RowEditing"
OnRowCommand = "GridView2_RowCommand"
OnRowDeleting = "GridView2_RowDeleting"
OnRowDeleted = "GridView2_RowDeleted"
OnRowUpdating = "GridView2_RowUpdating"
OnRowUpdated = "GridView2_RowUpdated"
OnRowCancelingEdit = "GridView2_CancelingEdit"
OnRowDatabound="GridView2_RowDataBound"
CssClass="mGrid"
PagerStyle-CssClass="pgr"
>
<HeaderStyle Font-Bold="True" ForeColor="White" />
<Columns>
<asp:TemplateField HeaderText="Step Type">
<ItemTemplate><%#Eval("STEP_TYPE")%></ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="ddl_StepTypes"
DataSourceID="ds_StepTypes"
SelectedValue='<%# Eval("STEP_TYPE_ID")%>'
DataTextField="STEP_TYPE"
DataValueField="STEP_TYPE_ID"
runat="server"
Width="100px"
Font-Size="X-Small"
AutoPostBack="true"
OnSelectedIndexChanged = "ddl_StepTypes_SelectedIndexChanged">
</asp:DropDownList>
<label id="lblTest"></label>
<!--<asp:TextBox ID="txtStepType" Text='<%# Eval("SERVER_ID")%>' runat="server"></asp:TextBox>-->
</EditItemTemplate>
<FooterTemplate>
<asp:DropDownList DataSourceID="ds_StepTypes"
DataTextField="STEP_TYPE" DataValueField="STEP_TYPE_ID" ID="ddl_StepTypes" runat="server" Width="100px" Font-Size="X-Small"></asp:DropDownList>
<!--<asp:TextBox ID="txtStepType" Text='' runat="server"></asp:TextBox>-->
</FooterTemplate>
</asp:TemplateField>
If any more information is needed, please let me know. Thank you.

Answer 1

The problem is that if you add a control to a template, the GridView creates multiple copies of that control, one for each data item. When the item is chosen, you need a way to determine which Dropdownlist was clicked and which row it belongs to.
The way to resolve this problem is to use an event from the GridView.
The GridView.RowCommand event serves this purpose. Unfortunately initially it is supposed to fire whenever any button is clicked in any template. This process, where a control event in a template is turned into an event in the containing control, is called event bubbling.
May be a workaround described here can help you. Alternatively may be this article could also help (or another one referenced at the very bottom).