DataList problem

aszyk · Apr 28, 2012

Hi All, I have a problem with a DataList in a UserControl (code below). This DataList SHOULD display the three names in ArrayList "myAL" as soon as MainPage.aspx is loaded into the browser, but it does NOT. However, strangely, when the LinkButton in the UserControl is clicked, the three names in ArrayList "myAL" AND the three names in ArrayList "MyAL2" are displayed. I hope someone out there can explain why the "myAL" names aren't displayed as soon as the page renders - this is what I was trying to achieve. Thanks in advance, JON PS This posting is a much briefer version of the (unanswered) one titled "Why won't DataList display when page renders?", sent to this forum on 5/17/2002. ++++++++++++++++++++++++ MainPage.aspx ++++++++++++++++++++++++ <%@ Page Language="VB" debug="true" trace="true" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.Oledb" %> <%@ Register TagPrefix="User" TagName="Control" src=http://aspmessageboard.com/archive/index.php/"UserControl.ascx" %> <script language="VB" runat="server"> Sub Page_PreRender(obj as object, e as EventArgs) If not Page.IsPostBack then Dim myAL As New ArrayList() myAL.Add("Bob") myAL.Add("Jimmy") myAL.Add("Eric") '*** The names Bob, Jimmy and Eric '*** should be visible when this page first displays '*** but they are not '*** WHY?????? '*** These names DO become visible, however '*** when the LinkButton is clicked '*** WHY?????? Dim myEnumerator As System.Collections.IEnumerator = myAL.GetEnumerator() While myEnumerator.MoveNext() UserControl.AddPerson(myEnumerator.Current, 1) End While end if end sub Public Sub DisplayNames(obj as object, e as eventargs) Dim myAL2 As New ArrayList() myAL2.Add("Michael") myAL2.Add("Jack") myAL2.Add("Earl") '*** This subroutine works normally '*** displaying the names Michael, Jack and Earl '*** every time the LinkButton is clicked Dim myEnumerator As System.Collections.IEnumerator = myAL2.GetEnumerator() While myEnumerator.MoveNext() UserControl.AddPerson(myEnumerator.Current, 1) End While End Sub </script> <html> <form runat="server"> <User:Control runat="server" id="UserControl" /> <asp:LinkButton text="click" runat="server" OnClick="DisplayNames" /> </form> </html> ++++++++++++++++++++++++ UserControl.ascx ++++++++++++++++++++++++ <%@ Control Language="VB" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.Oledb" %> <script language="VB" runat="server"> Dim myDataTable as DataTable Sub Page_Load(obj as object, e as eventargs) If Not IsNothing(ViewState("PeopleToAdd")) then myDataList.DataSource = ViewState("PeopleToAdd") DataBind() end if If not Page.IsPostBack '*** Set up the DataTable "PeopleToAdd" in memory myDataTable = new DataTable("PeopleToAdd") Dim myColumn as DataColumn myColumn = myDataTable.Columns.Add("PersonID", System.Type.GetType("System.Int32")) myColumn.AllowDBNull = false myColumn = myDataTable.Columns.Add("Name", System.Type.GetType("System.String")) myColumn.AllowDBNull = false ViewState("PeopleToAdd") = myDataTable DataBind() end if end sub Public Sub AddPerson(SelectedPersonName as String, SelectedPersonValue as Integer) '*** Pull the DataTable out of the ViewState myDataTable = ViewState("PeopleToAdd") '*** Add the row to the DataTable Dim myRow as DataRow myRow = myDataTable.NewRow() myRow("PersonID") = SelectedPersonValue myRow("Name") = SelectedPersonName myDataTable.Rows.Add(myRow) '*** Put everything back in the ViewState ViewState("PeopleToAdd") = myDataTable myDataList.DataBind() End sub </script> <asp

ataList runat="server" id="myDataList" repeatlayout = "flow" repeatdirection = "horizontal"> <ItemTemplate> <asp:LinkButton runat="server" Text='<%# Container.DataItem("Name") %>'/> </ItemTemplate> </asp

ataList> Hi All, I solved the problem eventually. InUserControl.ascx, I had to move the line: myDataList.DataSource = ViewState("PeopleToAdd") into the Page_Load If Not Page.IsPostBack subroutine, giving this: If not Page.IsPostBack myDataTable = new DataTable("PeopleToAdd") myColumn = myDataTable.Columns.Add("PersonID", System.Type.GetType("System.Int32")) myColumn.AllowDBNull = false myColumn = myDataTable.Columns.Add("Name", System.Type.GetType("System.String")) myColumn.AllowDBNull = false ViewState("PeopleToAdd") = myDataTable myDataList.DataSource = ViewState("PeopleToAdd") '**** PUT THE LINE HERE INSTEAD! DataBind() end if Cheers, JON

DataList problem

aszyk

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