Issue Creating Custom ListView LayoutTemplate

Question

User1342168525 posted

Hello,

I am working on a project where I will be displaying a set of data, however, depending on the user's settings, the columns that will be displayed will vary greatly. I am using a ListView control because of its flexible template system. I will need to define the template at run-time, since I will never know what columns need to be created and displayed until then.

So I decided to create my own LayoutTemplate and ItemTemplate classes. I am running into an issue with the LayoutTemplate (have not tried the ItemTemplate yet).

When I run my code, I get the following error:

An item placeholder must be specified on ListView ''. Specify an item placeholder by setting a control's ID property to "itemPlaceholder". The item placeholder control must also specify runat="server".

Here is the code for my LayoutTemplate class:

Public Class v_LayoutTemplate
    Implements ITemplate

    Private _strcolconfig As String

    Public Sub New(ByVal colconfig As String)
        _strcolconfig = colconfig
    End Sub

    Public Sub InstantiateIn(ByVal container As System.Web.UI.Control) Implements System.Web.UI.ITemplate.InstantiateIn
        'create a new HTML table object and set its attributes...
        Dim t As New HtmlGenericControl("table")
        t.Attributes.Add("class", "j-table")
        t.Attributes.Add("cellpadding", "3")
        t.Attributes.Add("cellspacing", "0")

        'add a table header to the table...
        Dim thead As New HtmlGenericControl("thead")

        'add the new table row objects...
        Dim tr As New HtmlGenericControl("tr")
        tr.Attributes.Add("class", "rpt_header_row")

        'create the initial columns used for icons...
        Dim th As New HtmlGenericControl("th")
        th.Attributes.Add("class", "ignore-drop")
        th.Attributes.Add("style", "border-left: solid 1px #275d86;")
        th.InnerHtml = " "
        tr.Controls.Add(th)

        th = New HtmlGenericControl("th")
        th.InnerHtml = " "
        tr.Controls.Add(th)

        'split the configuration string to get the list of columns we have to create...
        Dim arrCol As String() = _strcolconfig.Split("|")

        'create each of the content column headers...
        For Each s As String In arrCol
            th = New HtmlGenericControl("th")
            th.InnerHtml = "<divdrag"">" & s & "</div>"
            tr.Controls.Add(th)
        Next

        'add the closing column used for drag and drop purposes...
        th = New HtmlGenericControl("th")
        th.Attributes.Add("class", "ignore-drop")
        th.Attributes.Add("style", "border-right: solid 1px #275d86;")
        th.InnerHtml = "&nbsp;"
        tr.Controls.Add(th)

        thead.Controls.Add(tr)

        t.Controls.Add(thead)

        'create the tbody object...
        Dim tbody As New HtmlGenericControl("tbody")

        'Dim trph As New HtmlGenericControl("tr")
        'trph.Attributes.Add("runat", "server")
        'trph.Attributes.Add("id", "itemPlaceholder")

        Dim ph As New PlaceHolder()
        ph.ID = "itemPlaceholder"

        tbody.Controls.Add(ph)
        t.Controls.Add(tbody)
    End Sub
End Class

At runtime, I already have the ListView control on my webform and have simply left off the LayoutTemplate portion. (I know this is not the proper way, but I am only doing this for testing to see if I can get this to work)

Private Sub BindData()
        lvReport.LayoutTemplate = New v_LayoutTemplate("File No.|Cust No.|Opened|Entry No.|Concept|SCAC|Desc. Of Goods|ETA POE|ETA POI|ETA Dest.")

        Dim cmd As New SqlCommand("test_ReturnData", conn)
        cmd.CommandType = CommandType.StoredProcedure
        conn.Open()
        Dim rd As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)

        With lvReport
            .DataSource = rd
            .DataBind()
        End With
        rd.Close()
    End Sub

I can't seem to find a lot of detailed on this info out on the net. Any help would be greatly appreciated.

Thanks!

Bob Gibilaro