Dynamically created DropDownList in DataGrid problem

[Norkis]

Hello,

Please check am I doing this correctly and why I'm loosing selectedvalue of dropdownlist.

In Page_Int I create DataGrid dynamicaly.

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
 
            InitializeComponent()
                Dim DGlist As New DataGrid
                DGlist.ID = "DGlist"
                DGlist.CellPadding = 7
                DGlist.HeaderStyle.CssClass = "SubSubHead"
                DGlist.ItemStyle.CssClass = "Normal"
                ' DGlist.EnableViewState = False
                DGlist.AutoGenerateColumns = False
                RegContentPane.Controls.Add(DGlist)

Becouse I do not know how many columns I would get I must create all TemplateColumns dynamicaly fo datagrid. In Page_Load I fire sub, that gets dataset, creates datagrid columns according to it and then binds it.

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
             
                                     Call Submitas(sender, e)
        End Sub
 
 Private Sub Submitas(ByVal sender As System.Object, ByVal e As System.EventArgs)
            Dim DGlist As DataGrid, DS As New DataSet
DGlist = RegContentPane.FindControl("DGlist")
 
            DS = ListDB.GetColumns(ModuleId)
 
for each ....
'Then I loop throught each column and add it.
Dim tc2 As New TemplateColumn
                    tc2.HeaderTemplate = New DataGridTemplate(ModuleId,SysName, Name, type)
                    tc2.ItemTemplate = New DataGridTemplate(ModuleId, SysName, Name, type)
                    tc2.EditItemTemplate = New DataGridTemplate(ModuleId, SysName, Name, type)
                    DGlist.Columns.Add(tc2)
next
 
 If Not DS Is Nothing Then
                DGlist.DataSource = DS
                DGlist.DataBind()
            End If
end sub
 
Private Sub dg_ItemCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs)
            Dim dg As DataGrid = CType(source, DataGrid), ListDB As New ASPNetPortal.ListDB
            Select Case e.CommandName
 
                Case "Edit"
 
                    dg.EditItemIndex = e.Item.ItemIndex
                     dg.DataBind()
            End Select
 
        End Sub
 
        Private Class DataGridTemplate
            Implements ITemplate
            Dim templateType As ListItemType
            Dim ModuleId, syscolumnName, columnName As String
            Dim type As Int16
 
            Sub New(ByVal ModuleId As String, ByVal lstType As ListItemType, ByVal SysColName As String, ByVal ColName As String, ByVal colType As Int16)
                Me.ModuleId = ModuleId
                templateType = lstType
                columnName = ColName
                syscolumnName = SysColName
                type = colType
            End Sub
 
            Sub InstantiateIn(ByVal container As Control) _
               Implements ITemplate.InstantiateIn
 
 
                Dim lc As New Literal, ListDB As New ASPNetPortal.ListDB
                Select Case templateType
                    Case ListItemType.Header
                        lc.Text = columnName
                        container.Controls.Add(lc)
 
 
                    Case ListItemType.Item
                        If type = -1 Then
                            Dim imb As New ImageButton
                            imb.ID = "editbtn"
                            imb.CommandName = "Edit"
                            imb.ImageUrl = "~/images/edit.gif"
                            container.Controls.Add(imb)
                        Else
                            lc.Text = columnName
                            AddHandler lc.DataBinding, AddressOf DataGridTemplate_DataBinding
                            container.Controls.Add(lc)
                        End If
                    Case ListItemType.EditItem
                        Select Case type
                            Case -1
                                Dim imb As New ImageButton
                                imb.ID = "updatebtn"
                                imb.CommandName = "Update"
                                imb.ImageUrl = "~/images/update.gif"
                                container.Controls.Add(imb)
                                imb = New ImageButton
                                imb.ID = "cancelbtn"
                                imb.CommandName = "Cancel"
                                imb.ImageUrl = "~/images/cancel.gif"
                                container.Controls.Add(imb)
                            Case 0
                                lc.Text = columnName
                                AddHandler lc.DataBinding, AddressOf DataGridTemplate_DataBinding
                                container.Controls.Add(lc)
                            Case 1
                                Dim tb As New TextBox
                                tb.ID = columnName
                                AddHandler tb.DataBinding, AddressOf Control_DataBinding
                                container.Controls.Add(tb)
                            Case 2 'dropdownlist
                                Dim ddl As New DropDownList
                                ddl.ID = columnName
                                Dim ds As New DataSet
 
                                ds = ListDB.GetColumnData(ModuleId, syscolumnName)
                                ddl.DataTextField = "Caption"
                                ddl.DataValueField = "Caption"
                                ddl.DataSource = ds
                                ddl.DataBind()
                                container.Controls.Add(ddl)
                                'ddl.SelectedValue = CType(container, DataGridItem).DataItem(columnName)
                                AddHandler ddl.DataBinding, AddressOf Control_DataBinding
 
 
                        End Select
 
 
                    Case ListItemType.Footer
                        lc.Text = "Footer"
                        container.Controls.Add(lc)
                End Select
 
 
            End Sub
 
 
            Private Sub DataGridTemplate_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
                Dim container As DataGridItem
                Dim lc As Literal
 
                lc = CType(sender, Literal)
                container = CType(lc.NamingContainer, DataGridItem)
                If Not IsDBNull(container.DataItem(lc.Text)) Then
                    lc.Text = container.DataItem(lc.Text)
                Else
                    lc.Text = ""
                End If
 
            End Sub
 
 
            Private Sub Control_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
                Dim container As DataGridItem
                Dim lc As Object
 
                Select Case sender.GetType.Name
                    Case "TextBox"
                        lc = CType(sender, TextBox)
                        container = CType(lc.NamingContainer, DataGridItem)
                        If Not IsDBNull(container.DataItem(lc.ID)) Then
                            lc.Text = container.DataItem(lc.ID)
                        End If
                    Case "DropDownList"
                        lc = CType(sender, DropDownList)
                        container = CType(lc.NamingContainer, DataGridItem)
                        If Not IsDBNull(container.DataItem(lc.id)) Then
                            CType(lc, DropDownList).SelectedValue = container.DataItem(lc.id)
                        End If
                End Select
 
 
            End Sub
        End Class
 
    End Class

This code works fine except with dropdownlist. Then I press edit button, dropdownlist bind, but selected value is lost. With textbox, it's working fine.

Hope somebody can help me.

[Nikhil Aggarwal]

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
             
                                     [COLOR=Red]Call Submitas(sender, e)[/COLOR]
        End Sub

Offhand this is the only thing I could notice:
There is no check for IsPostBack value. So when you click on Edit, the page posts back, Submitas is called and the datagrid is repopulated.
Try enclosing the call to Submitas in

If Not IsPostBack Then
 
        End If

[Norkis]

If I do this, columns aren't recreated, data isn't rebinded and I don't got datagrid visible.