HELP - Session et datatable

Imports System.Xml
Imports System.Collections.ObjectModel


Partial Class _Default
    Inherits System.Web.UI.Page



    Private strOutput As String = ""
    Private PathOfXML As String = "\\10.15.78.216\transition\pubs.xml"
    Private Tab() As String = {"datedebut", "datefin", "titre", "prixbase", "prixpromo", "categorie", "calibre", "origine", "photo"}


    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            'Chargement des photos dans une DropDownList
            Dim files As String() = System.IO.Directory.GetFiles(Server.MapPath("~/photo/"), "*.jpg")
            For Each f As String In files
                ddl.Items.Add(System.IO.Path.GetFileName(f))
            Next
            ChargementXML()
        End If

    End Sub

    Protected Sub ChargementXML()
        Dim xmldoc As New XmlDataDocument()

        Try
            xmldoc.DataSet.ReadXml(PathOfXML)

            GridView1.DataSource = xmldoc.DataSet
            GridView1.DataMember = xmldoc.DataSet.Tables(0).TableName

            GridView1.DataBind()

            Session("pubs") = xmldoc.DataSet.Tables(0)

        Catch ex As Exception
            strOutput = "Impossible d'accéder au fichier XML" & "<br />" & ex.Message.ToString
        End Try

        output.Text = strOutput
    End Sub

    Protected Sub GridView1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles GridView1.SelectedIndexChanged
        GridView1.SelectedIndex = -1
    End Sub

    Protected Sub GridView1_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles GridView1.RowCommand
        Select Case e.CommandName
            Case "Select", "Edit"
                For Each t As String In Tab
                    Select Case t
                        Case "photo"
                            Dim Photo As String = CType(GridView1.Rows(e.CommandArgument.ToString).FindControl(t & "LabelGV"), Label).Text
                            CType(Panel1.FindControl(t & "Image"), Image).ImageUrl = "~/Photo/" & Photo
                            CType(Panel1.FindControl(t & "Image"), Image).AlternateText = "~/Photo/" & Photo
                            For i As Integer = 0 To ddl.Items.Count - 1
                                If ddl.Items(i).Text = Photo Then
                                    ddl.SelectedIndex = i
                                    Exit For
                                End If
                            Next
                        Case "prixbase", "prixpromo"
                            CType(Panel1.FindControl(t & "Label"), Label).Text = CType(GridView1.Rows(e.CommandArgument.ToString).FindControl(t & "LabelGV"), Label).Text & " ¤"
                            CType(Panel2.FindControl(t & "Tb"), TextBox).Text = CType(GridView1.Rows(e.CommandArgument.ToString).FindControl(t & "LabelGV"), Label).Text
                        Case Else
                            CType(Panel1.FindControl(t & "Label"), Label).Text = CType(GridView1.Rows(e.CommandArgument.ToString).FindControl(t & "LabelGV"), Label).Text
                            CType(Panel2.FindControl(t & "Tb"), TextBox).Text = CType(GridView1.Rows(e.CommandArgument.ToString).FindControl(t & "LabelGV"), Label).Text
                    End Select
                Next
                If e.CommandName = "Edit" Then
                    modeLabel.Text = "Modification"
                    hfIdRow.Value = e.CommandArgument
                End If
                CType(UpdatePanel1.FindControl("mpePanel" & e.CommandName), AjaxControlToolkit.ModalPopupExtender).Show()
            Case "Delete"
                ActionOnXML(e.CommandName, e.CommandArgument.ToString)
            Case Else
                ActionOnXML(e.CommandName, e.CommandArgument.ToString)
        End Select
    End Sub

    Protected Sub ActionOnXML(ByVal mode As String, Optional ByVal idOfArticle As Integer = -1)
        Dim dt As New Data.DataTable
        dt = Session("pubs")

        Select Case mode
            Case "Add", "Ajout"
                Dim nr As Data.DataRow = dt.NewRow
                dt.Rows.Add(AddModifArticle(nr))
            Case "Edit", "Modification"
                Dim cr As Data.DataRow = dt.Rows(idOfArticle)
                AddModifArticle(cr)
            Case "Delete"
                dt.Rows(idOfArticle).Delete()
                log.Text += Date.Now.ToString & " : Nombre de DataRow = " & dt.Rows.Count & "<br />"
                log.Text += "ActionOnXML : " & mode & " (" & idOfArticle & ")<br /><br />"
        End Select

        GridView1.DataSource = dt
        GridView1.DataBind()
    End Sub

    Private Function AddModifArticle(ByVal dr As Data.DataRow) As Data.DataRow
        For Each t As String In Tab
            Select Case t
                Case "photo"
                    dr(t) = ddl.SelectedItem.Text
                Case Else
                    dr(t) = CType(Panel2.FindControl(t & "Tb"), TextBox).Text
            End Select
        Next
        Return dr
    End Function

    Protected Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting
        e.Cancel = True
    End Sub
    Protected Sub GridView1_RowEditing(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewEditEventArgs) Handles GridView1.RowEditing
        e.Cancel = True
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bRec.Click
        Dim dt As Data.DataTable = Session("pubs")
        dt.DataSet.WriteXml(PathOfXML)
    End Sub

    Protected Sub GridView1_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles GridView1.PreRender
        output.Text = GridView1.Rows.Count & " articles trouvés."
    End Sub

    Protected Sub bValid_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bValid.Click
        ActionOnXML(modeLabel.Text, hfIdRow.Value)
    End Sub

    Protected Sub lbAddPub_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles lbAddPub.Click
        For Each t As String In Tab
            Select Case t
                Case "photo"
                    ddl.SelectedIndex = 0
                Case Else
                    CType(Panel2.FindControl(t & "Tb"), TextBox).Text = ""
            End Select
        Next
        modeLabel.Text = "Ajout"
        mpePanelEdit.Show
    End Sub
End Class