Getting Dynamic controls to persist

Workin a DB search page where the enduser can build a custom search so I must add controls to the page as the search items are selected. Well I got that part done by looping thru a Session object I used to store the searchfield names. Well now I go and add some value to the page and then when I try to add another search item to the page I have to refresh it to do so. Well now any text I have put into a textbox is now gone because I had to reload all the controls when something is added. So I need to know is there a way to retain that text/selection when added or add controls without refreshing the page.

Here is my current code for adding search items

Code:

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Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load


        If Not Page.IsPostBack Then
            GetField()
            reslist()
        End If


    End Sub

   
   
       
   


    Function GetField()
       
        Session("SearchItems") = "By Town,Status,List Price Range,Bedrooms,Full Baths,Total SqFt (gla),Year Built"
        Session("sys_name") = "town,status,list_price,bedrooms,baths,glaag,year_built"
        Session("condition") = "=,=,bt,bt,bt,bt,bt"
        Session("val1") = "0,0,0,1,1,0,1800"
        Session("val2") = "0,0,99900020,20,99999,2003"
        Session("vi_type") = "TOWN,STATUS,RANGE,RANGE,RANGE,RANGE,RANGE,"
        Session("vi_translation") = "MADAREA,STATUS, , , , , "
        Session("ttlitems") = 7

        FillPanel()
    End Function

    Function getcondition(ByVal vtype As String, ByVal actual As String, ByVal name As String, ByVal condition As String, ByVal translation As String)
        If condition = "=" And (translation = " " Or translation = "") Then

            Dim s As New TextBox
            s.EnableViewState = True
            s.ID = name
            Panel1.Controls.Add(s)
        End If
        If condition = "=" And translation = "MADAREA" Then
            Dim f As New ListBox
            f.Rows = 5
            f.EnableViewState = True
            f.SelectionMode = ListSelectionMode.Multiple
            f.ID = name
            f.DataTextField = "name"
            Dim conn As String
            Dim appsetting As NameValueCollection = CType(HttpContext.Current.GetConfig("appSettings"), NameValueCollection)
            conn = CStr(appsetting("dsnNH"))
            Dim myConnection As SqlConnection = New SqlConnection(conn)
            Dim dsLogin As SqlCommand
            If name = "county" Then
                dsLogin = New SqlCommand("select name from major_area", myConnection)
            Else
                dsLogin = New SqlCommand("select name from mls_area", myConnection)
            End If
            Dim dr As SqlDataReader
            myConnection.Open()
            dr = dsLogin.ExecuteReader()
            f.EnableViewState = True
            f.DataSource = dr
            f.DataBind()
            Panel1.Controls.Add(f)

            dr.Close()

        End If
        If condition = "=" And translation = "STATUS" Then
            Dim f As New DropDownList
            f.ID = name
            f.EnableViewState = True
            f.Items.Add("Current")
            f.Items.Add("Pending")
            f.Items.Add("Sold")
            f.Items.Add("Expired")
            f.Items.Add("Withdrawn")
            Panel1.Controls.Add(f)
        End If
        If condition = "bt" And (translation = " " Or translation = "") Then

            Dim s As New TextBox
            s.ID = name & "min"
            s.EnableViewState = True
            Panel1.Controls.Add(s)
            Panel1.Controls.Add(New LiteralControl(" and "))
            Dim t As New TextBox
            t.ID = name & "max"
            t.EnableViewState = True
            Panel1.Controls.Add(t)

        End If
        If condition = "cn" And translation = "" And Not name = "features" Then
            Dim d As New DropDownList
            d.ID = name & "cn"
            d.EnableViewState = True
            d.Items.Add("Contains")
            Panel1.Controls.Add(d)
        End If
        If condition = ">=" Or condition = "<=" Or condition = ">" Or condition = "<" Then
            Dim d As New DropDownList
            d.ID = name & "cn"
            d.EnableViewState = True
            d.Items.Add(condition)
            Panel1.Controls.Add(d)
        End If
                If condition = "=" And translation = "YNU" Then
            Dim d As New DropDownList
            d.ID = name
            d.EnableViewState = True
            d.Items.Add("Yes")
            d.Items.Add("No")
            d.Items.Add("Unknown")
            Panel1.Controls.Add(d)
        End If
        If condition = "cn" And translation = "UPPERSPACE" Then
            Dim t As New TextBox
            t.ID = name
            t.EnableViewState = True
            Panel1.Controls.Add(t)
        End If
        If condition = "=" And translation = "UPPERSPACE" Then
            Dim t As New TextBox
            t.ID = name
            t.EnableViewState = True
            Panel1.Controls.Add(t)
        End If
    End Function
   
    Private Sub ddsearch2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddsearch2.SelectedIndexChanged

        If InStr(Session("SearchItems"), Trim(ddsearch2.SelectedValue)) And Not Trim(ddsearch2.SelectedValue) = "Baths" Then

            lblExists.Visible = True
            FillPanel()

            Exit Sub
        Else
            lblExists.Visible = False
        End If
        Dim stype As String
        Dim conn As String
        Dim appsetting As NameValueCollection = CType(HttpContext.Current.GetConfig("appSettings"), NameValueCollection)
        conn = CStr(appsetting("dsnNH"))
        Dim myConnection As SqlConnection = New SqlConnection(conn)
        Dim dsLogin As SqlCommand = New SqlCommand("select type from search_tree where class_filter like '1%' and name='" & Trim(ddsearch2.SelectedValue) & "'", myConnection)
        Dim ds As SqlDataReader
        myConnection.Open()
        ds = dsLogin.ExecuteReader()
        Do While ds.Read()
            stype = Trim(ds("type").ToString())
        Loop

        ds.Close()
        myConnection.Close()

        If stype = "H" Then
           
    Private Sub ddSearch3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddSearch3.SelectedIndexChanged
        Dim conn As String
        Dim appsetting As NameValueCollection = CType(HttpContext.Current.GetConfig("appSettings"), NameValueCollection)
        conn = CStr(appsetting("dsnNH"))
        Dim myConnection As SqlConnection = New SqlConnection(conn)
        Dim dsLogin3 As SqlCommand = New SqlCommand("select name,sys_name,condition,vi_translation,vi_type from search_tree where name='" & Trim(ddsearch2.SelectedValue) & "' and class_filter like '1%'", myConnection)
        Dim ds3 As SqlDataReader
        myConnection.Open()
        ds3 = dsLogin3.ExecuteReader()
       
        Do While ds3.Read()

            Session("SearchItems") = Session("SearchItems") & "," & ds3("name").ToString()
            Session("sys_name") = Session("sys_name") & "," & ds3("sys_name").ToString()
            Session("condition") = Session("condition") & "," & ds3("condition").ToString()
            'Session("val1") = Session("val1") & "," & ds3("min").ToString()
            'Session("val2") = Session("val2") & "," & ds3("max").ToString()
            Session("vi_type") = Session("vi_type") & "," & ds3("vi_type").ToString()
            Session("vi_translation") = Session("vi_translation") & "," & ds3("vi_translation").ToString()
            Session("ttlitems") = Session("ttlitems") + 1
        Loop
        FillPanel()
        ds3.Close()
        myConnection.Close()
    End Sub
    Function FillPanel()
        Dim name(20) As String
        Dim s_name(20) As String
        Dim cond(20) As String
        Dim v1(20) As String
        Dim v2(20) As String
        Dim vityp(20) As String
        Dim vitrans(20) As String
        Dim i As Integer
        name = Split(Session("SearchItems"), ",")
        s_name = Split(Session("sys_name"), ",")
        cond = Split(Session("condition"), ",")
        v1 = Split(Session("val1"), ",")
        v2 = Split(Session("val2"), ",")
        vityp = Split(Session("vi_type"), ",")
        vitrans = Split(Session("vi_translation"), ",")
        For i = 0 To (Session("ttlitems") - 1)
            Panel1.Controls.Add(New LiteralControl("<table>"))
            Dim l As New Label
            l.ID = s_name(i) & "lbl" & i
            l.Text = name(i)
            'label1.EnableViewState = True
            'l.Font.Name = "Ms sans Serif;10pt"
            Panel1.Controls.Add(New LiteralControl("<tr><td align=left width=150>"))
            Panel1.Controls.Add(l)
            Panel1.Controls.Add(New LiteralControl("</td><td>"))
            getcondition(vityp(i), name(i), s_name(i), cond(i), vitrans(i))
            'getsearch(ds("sys_name").ToString() & "cn", ds("condition").ToString(), ds("vi_translation").ToString())
            Panel1.Controls.Add(New LiteralControl("</td></tr>"))
            Panel1.Controls.Add(New LiteralControl("</table>"))
        Next
    End Function

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You need to make sure that any controls that are added dynamically are recreated before the postback change events fire. This will require you to maintain a list of controls you added so you can recreate them on postback.

I've used ViewState for this. You can create an ArrayList containing the names of the ID's of the controls you've added. Persist this to ViewState. Then on every postback check if that ArrayList is in ViewState, if it is then spin through each item and recreate the control and add it to your panel or whatever BEFORE the postback change events fire(i.e. no later than the Page Load event), that way the values in your dynamically added controls will persist properly.

This approach is easy if you're always adding the same type of control, it gets complicated if you're adding a bunch of different control types, then you'll need to persist the ID of the control as well as the type of control. A cool way to store both items is to use a Triplet object, then save the Triplet object to your arraylist and again persist the arraylist to viewstate.