remove a row from radgrid

[Myriam]

Hello
I have a Radgrid in a webform that contain only one combobox in each row. That combo box contain city. It is used to calculate how many kilometers it has between each city. (Like google). I am able to add line dynamicly and remove line too. When I remove line, it's always the last row that I'm taking off. And after, I rebind my datagrid. The thing is, all my combobox before lose there value the user selected. It put back the default value.
How can I keep the values the user selected in others combobox?
Here is my code:

<telerik:RadGrid
       ID="RadGrid2"
       Skin="Vista"
       runat="server"
       ShowFooter="true"
       CommandItemStyle-HorizontalAlign="Center" Width="200px">

       <MasterTableView
            ShowFooter="true"
            CommandItemDisplay="bottom"
            EditMode="InPlace" >
            <CommandItemTemplate>
                <asp:LinkButton ID="LinkButton1" Visible="false" CommandName="CalculDistance" Runat="server" CssClass="TexteBlanc16">Calculer</asp:LinkButton>
            </CommandItemTemplate>
            <Columns>
                 <telerik:GridTemplateColumn UniqueName="CodePostal" HeaderText="Destinations">
                        <ItemTemplate>
                                 <asp:DropDownList ID="LstCodePostal" runat="server"></asp:DropDownList>
                         </ItemTemplate>
                  </telerik:GridTemplateColumn>
            </Columns>
      </MasterTableView>
</telerik:RadGrid>
<asp:Panel ID="Panel1" runat="server">
      <asp:LinkButton ID="LKBtnAjouterDestination" runat="server">Ajouter une destination</asp:LinkButton>
      <asp:LinkButton ID="LKBtnEnleverDestination" runat="server">Enlever une destination</asp:LinkButton>
 </asp:Panel>

Public dt As DataTable
  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
      If Not IsPostBack = True Then
          dt = New DataTable()
          dt.Columns.Add(New DataColumn("RowNumber", GetType(String)))
          AjouterLigne(dt)
      End If

 Private Sub LKBtnAjouterDestination_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles LKBtnAjouterDestination.Click
        Dim countitem As Integer
        Dim dt As DataTable = DirectCast(ViewState("dt"), DataTable)

        countitem = RadGrid2.Items.Count
        Dim cpt As Integer = 0
        For Each Item As GridDataItem In RadGrid2.Items

            Dim Lstcode As DropDownList = DirectCast(Item("CodePostal").FindControl("LstCodePostal"), DropDownList)
            If Not (Lstcode.Text Is Nothing) And Lstcode.Text <> "" Then
                liste.Add(Lstcode.Text)
            End If

        Next
        ViewState("dt") = AjouterLigne(dt)
        listcount = liste.Count

        RadGrid2.Rebind()

        While cpt < listcount
            Dim Lstcode As DropDownList = DirectCast(RadGrid2.Items(cpt)("CodePostal").FindControl("LstCodePostal"), DropDownList)
            Lstcode.Text = liste.Item(cpt)
            cpt = cpt + 1
        End While
    End Sub

    Private Sub LKBtnEnleverDestination_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles LKBtnEnleverDestination.Click
        Dim countitem As Integer
        Dim dt As DataTable = DirectCast(ViewState("dt"), DataTable)

        countitem = RadGrid2.Items.Count

        ViewState("dt") = EnleverLigne(dt, countitem)
        listcount = liste.Count

        RadGrid2.Rebind()

    End Sub

    Public Function AjouterLigne(ByVal dt As DataTable) As DataTable
        ' method to create row
        Dim dr As DataRow = dt.NewRow()
        dr("RowNumber") = ""
        dt.Rows.Add(dr)
        Return dt
    End Function

    Public Function EnleverLigne(ByVal dt As DataTable, ByVal IndexDernier As Integer) As DataTable
        ' method to delete row
        If IndexDernier > 0 Then
            dt.Rows(IndexDernier - 1).Delete()
        End If
        Return dt
    End Function

    Private Sub RadGrid2_ColumnCreated(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridColumnCreatedEventArgs) Handles RadGrid2.ColumnCreated
        If (e.Column.UniqueName = "RowNumber") Then
            e.Column.Visible = False
        End If
    End Sub

    Private Sub RadGrid2_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridItemEventArgs) Handles RadGrid2.ItemDataBound
        Dim cpt As Integer = 0
        Do While cpt < RadGrid2.Items.Count
            'Dim Lstcode As DropDownList = DirectCast(Item("CodePostal").FindControl("LstCodePostal"), DropDownList)
            Dim Lstcode As DropDownList = DirectCast(RadGrid2.Items(cpt)("CodePostal").FindControl("LstCodePostal"), DropDownList)
            Lstcode.DataSource = DsVilleCodePostal
            Lstcode.DataTextField = "VILLE"
            Lstcode.DataValueField = "CODE_POSTAL"
            Lstcode.DataBind()
            Lstcode.SelectedValue = "G5Y7R7"
            cpt = cpt + 1
        Loop


    End Sub

    Private Sub RadGrid2_NeedDataSource(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGrid2.NeedDataSource
        If Not IsPostBack Then
            dt = AjouterLigne(dt)
            ' call the method to create row
            ViewState("dt") = dt
        End If
        dt = DirectCast(ViewState("dt"), DataTable)
        RadGrid2.DataSource = dt

    End Sub

  Private Sub RadGrid2_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadGrid2.PreRender
        RadGrid2.MasterTableView.RenderColumns(1).Display = False
    End Sub

Thank you
Myriam

[Jayesh Goyani]

Hello,

This thing was not automatically managed due to stateless issue of browser.

solution 1 :
after clicked on delete and before perform delete operation you can save combobox state in session/viewstate.
after performed the delete operation it automatically called rebind event so
in itemDataBound event again set combobox value  using session/viewstate.

solution 2:
after the changing the value of combobox you can save their value in sesssion/viewstate
after performed the delete operation it automatically called rebind event so
in itemDataBound event again set combobox value  using session/viewstate.

Note : solution 1 is the best choice to achieve your requirement. 

let me know if any concern.

Thanks,
Jayesh Goyani

[Myriam]

Thank you for the reply.
Can you tell me how to put it in session/viewstate? I don't know what you mean.. sorry..
Thank you
Myriam