asked on

Need help with numeric pagelink, its one page behind.

Hi.

Im almost got this to work, but its a page behind.

I got some data 13 Records, 5 records on a page, give 3 pages.

if i start the script i get this page
Pagename.aspx (this page is page 1)
Pagename.aspx?Page=1 (this page is page 2)
Pagename.aspx?Page=2 (this page is page 3)

I need this to know that if Page = Nothing then Page=1
Can someone help me with the right page numeric number !?
So Page 3 is Pagename.aspx?Page=3
Page 2 = Pagename.aspx?Page=2
And Page 1 = Pagename.aspx and Pagename.aspx?Page=1

My code.

Imports System.Data
Imports System.Data.OleDb

Partial Class gridview_EX_Default2
    Inherits System.Web.UI.Page

    Dim pagedData As New PagedDataSource

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

    Public Function getTheData() As DataTable
        'Get data from DB using DataSet 
        Using connection As OleDbConnection = New OleDbConnection(ConfigurationManager.ConnectionStrings("MyConnStr").ConnectionString)
            Dim sql As String = "SELECT * FROM TableTest"
            Using adapter As OleDbDataAdapter = New OleDbDataAdapter(sql, connection)
                Dim ds As New DataSet()
                adapter.Fill(ds, "Portfolio_items")
                Return ds.Tables("Portfolio_items").Copy
            End Using
        End Using
    End Function

    Public Sub doPaging()
        pagedData.DataSource = getTheData().DefaultView
        pagedData.AllowPaging = True
        pagedData.PageSize = 5 'Maximum number of records to show per page

        Try
            pagedData.CurrentPageIndex = Int32.Parse(Request.QueryString("Page")).ToString()
        Catch ex As Exception
            pagedData.CurrentPageIndex = 0
        End Try

        btnPrev.Visible = (Not pagedData.IsFirstPage)
        btnNext.Visible = (Not pagedData.IsLastPage)
        btnFirst.Visible = (Not pagedData.IsFirstPage)
        btnLast.Visible = (Not pagedData.IsLastPage)

        pageNumber.Text = (pagedData.CurrentPageIndex) & " of " & pagedData.PageCount

        'Make the numeric pagelink
        If pagedData.CurrentPageIndex = 1 AndAlso pagedData.DataSourceCount > pagedData.PageSize Then
            pageNumberLink.Text = "Pages: 1"
        ElseIf pagedData.DataSourceCount = 0 Then
            pageNumberLink.Text = "No data to display."
        ElseIf pagedData.CurrentPageIndex > 1 AndAlso pagedData.DataSourceCount > pagedData.PageSize Then
            pageNumberLink.Text = "Pages: <a href='" & Request.CurrentExecutionFilePath & "?Page=1' style='text-decoration:none;' >1</a>"
        End If


        For i As Integer = 2 To pagedData.PageCount
            If i = pagedData.CurrentPageIndex Then
                pageNumberLink.Text = pageNumberLink.Text + " , " & i.ToString()
            Else
                pageNumberLink.Text = pageNumberLink.Text + " , <a href='" & Request.CurrentExecutionFilePath & "?Page=" & i.ToString() & "' style='text-decoration:none;'>" & i.ToString() & "</a>"

            End If
        Next

        'Print the data
        theDataList.DataSource = pagedData
        theDataList.DataBind()
        recordsCount.Text = pagedData.DataSourceCount 'Show Total Records

    End Sub

    Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnNext.Click
        Response.Redirect(Request.CurrentExecutionFilePath & "?Page=" & (pagedData.CurrentPageIndex + 1))
    End Sub

    Private Sub btnPrev_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnPrev.Click
        Response.Redirect(Request.CurrentExecutionFilePath & "?Page=" & (pagedData.CurrentPageIndex - 1))
    End Sub

    Private Sub btnLast_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnLast.Click
        Response.Redirect(Request.CurrentExecutionFilePath & "?Page=" & (pagedData.PageCount - 1))
    End Sub

    Private Sub btnFirst_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnFirst.Click
        Response.Redirect(Request.CurrentExecutionFilePath & "?Page=" & (pagedData.CurrentPageIndex = 0))
    End Sub

End Class

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Bob Learned

What kind of control are you using with the PagedDataSource? Are you handling binding different on page load and page post-back?

tjgrindsted

ASKER

hmm i dont know, im new to this, have that something to say !?

Bob Learned

It looks like the PagedDataSource is part of an extended GridView class (gridview_EX_Default2), but I can't see the HTML declaration for the control in the .aspx page or .ascx control...

tjgrindsted

ASKER

Ahh

Its bc i started to call the folder gridview_EX, but its a Datalist and its working fine, i just have some problems with the numeric link.

Bob Learned

I see this event handler:

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

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How are you handling it different when the page posts-back (i.e. If Not Page.IsPostBack Then)?

tjgrindsted

ASKER

its a code (without the numeric paginglink) i have found, and then im have tryed to add the numeric paginglink, there was no if not page.is postback, so i dont know that part, is that importent !? if yes how do i fix this error then !? as writing im new to this.

Bob Learned

Here is a simple introduction to ASP.NET post-backs:

IsPostBack in ASP.net
http://www.java-samples.com/showtutorial.php?tutorialid=1083

Important concept:

if (! IsPostBack)
   {
      //  Do the expensive operations only the 
      //  first time the page is loaded.
   }

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Persist the data to cache or session variable, and re-bind to a restored version, and don't re-bind with heavy operation again.

tjgrindsted

ASKER

ok but have the error something to do with the post back !?

Bob Learned

A lot of what happens with ASP.NET is about the page life-cycle, which post-backs are a major part of. I have no idea what the real problem is, but post-back handling is usually the first place I start to look.

I do see where you are loading the data from the database every time which is a fairly expensive operation, and should only be done on page load. The PagedDataSource should handle the paging after that.

tjgrindsted

ASKER

Ok i have looked at another ex. and i cant get the numeric paginglink to the Datalist ID="dlPaging".
I did what u ask me to, about PostBack I dont know if I load the Data from the DB to many times, but hope u can help me.
(again the folder the ex. is in, have the name "gridview_EX")

I get the data, the right Count and the Paging is working, im not getting the Numeric Paging link.

Code.

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default3.aspx.vb" Inherits="gridview_EX_Default3" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form ID="form1" runat="server">
    <div>
    
        <asp:Datalist ID="dListItems" runat="server" RepeatColumns="1" RepeatDirection="Horizontal">
     <ItemTemplate>
      <table border="0" cellpadding="0">
       <tr>
        <td>
         <font color="#49176d" size="2">
          <center><%# Eval("test_info")%></center>
         </font>
       <tr>
        <td>
         <%# Eval("test_cat") %>
        </td>
        </tr><tr>
        <td>
         <%# Eval("test_id")%>
         </tr><tr>
        <td>
         <%# Eval("test_dato", "{0:M-dd-yyyy}")%>
        </td>
        </td>
       </tr>
       </td> </tr>
      </table>
     </ItemTemplate>
    </asp:DataList>
        <asp:DataList ID="dlPaging"  runat="server" RepeatColumns="1" RepeatDirection="Vertical"></asp:DataList>

        <asp:ImageButton ID="lbtnFirst" runat="server" ImageUrl="images/paging_arrow_first.png"></asp:ImageButton>
        <asp:ImageButton ID="lbtnPrevious" runat="server" ImageUrl="images/paging_arrow_prev.png"></asp:ImageButton>
        <asp:ImageButton ID="lbtnNext" runat="server" ImageUrl="images/paging_arrow_next.png"></asp:ImageButton>
        <asp:ImageButton ID="lbtnLast" runat="server" ImageUrl="images/paging_arrow_last.png"></asp:ImageButton>
        <br /><br />
        <asp:Label ID="lblPageInfo" runat="server"></asp:Label>
        <br /><br />
        <asp:Label ID="lblRecordsCount" runat="server"></asp:Label>
    </div>
    </form>
</body>
</html>

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Code_Behind

Imports System.Data
Imports System.Data.OleDb

Partial Class gridview_EX_Default3
    Inherits System.Web.UI.Page


    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Not IsPostBack Then
            Me.BindItemsList()
        End If
    End Sub

    'There are three get, set properties, 1-CurrentPage (To keep current page index), 2-fistIndex & 3-lastIndex (These two properties are used to for paging DataList).
    Private Property CurrentPage() As Integer
        Get
            Dim objPage As Object = ViewState("_CurrentPage")
            Dim _CurrentPage As Integer = 0
            If objPage Is Nothing Then
                _CurrentPage = 0
            Else
                _CurrentPage = CInt(objPage)
            End If
            Return _CurrentPage
        End Get
        Set(value As Integer)
            ViewState("_CurrentPage") = value
        End Set
    End Property
    Private Property firstIndex() As Integer
        Get

            Dim _FirstIndex As Integer = 0
            If ViewState("_FirstIndex") Is Nothing Then
                _FirstIndex = 0
            Else
                _FirstIndex = Convert.ToInt32(ViewState("_FirstIndex"))
            End If
            Return _FirstIndex
        End Get
        Set(value As Integer)
            ViewState("_FirstIndex") = value
        End Set
    End Property
    Private Property lastIndex() As Integer
        Get

            Dim _LastIndex As Integer = 0
            If ViewState("_LastIndex") Is Nothing Then
                _LastIndex = 0
            Else
                _LastIndex = Convert.ToInt32(ViewState("_LastIndex"))
            End If
            Return _LastIndex
        End Get
        Set(value As Integer)
            ViewState("_LastIndex") = value
        End Set
    End Property

    'a PagedDataSource object to get and set various properties for custom paging.
    Dim pagedData As New PagedDataSource()

    'GetDataTable() method simply returns a DataTable.
    Private Function GetDataTable() As DataTable
        'Get data from DB using DataSet  
        Using connection As OleDbConnection = New OleDbConnection(ConfigurationManager.ConnectionStrings("MyConnStr").ConnectionString)
            Dim sql As String = "SELECT * FROM TableTest"
            Using adapter As OleDbDataAdapter = New OleDbDataAdapter(sql, connection)
                Dim ds As New DataSet()
                adapter.Fill(ds, "tb_Items")
                Return ds.Tables("tb_Items").Copy
            End Using
        End Using
    End Function

    'Method BindItemsList() gets DataTable by calling GetDataTable() method.
    Private Sub BindItemsList()
        Dim dataTable As DataTable = Me.GetDataTable()
        pagedData.DataSource = dataTable.DefaultView
        pagedData.AllowPaging = True
        pagedData.PageSize = 5 'Items on a site MAX 10.
        pagedData.CurrentPageIndex = CurrentPage
        ViewState("TotalPages") = pagedData.PageCount

        Me.lblPageInfo.Text = "Page " & (CurrentPage + 1) & " of " & pagedData.PageCount
        Me.lblRecordsCount.Text = "Total Records " & pagedData.DataSourceCount 'Show Total Records
        Me.lbtnPrevious.Visible = Not pagedData.IsFirstPage 'can be Visible or Enabled
        Me.lbtnNext.Visible = Not pagedData.IsLastPage 'can be Visible or Enabled
        Me.lbtnFirst.Visible = Not pagedData.IsFirstPage 'can be Visible or Enabled
        Me.lbtnLast.Visible = Not pagedData.IsLastPage 'can be Visible or Enabled

        Me.dListItems.DataSource = pagedData
        Me.dListItems.DataBind()
        Me.doPaging()
    End Sub

    'BindItemsList() calls doPaging() method which actually binds paging DataList.
    Private Sub doPaging()
        Dim dt As New DataTable()
        dt.Columns.Add("PageIndex")
        dt.Columns.Add("PageText")

        firstIndex = CurrentPage - 5

        If CurrentPage > 5 Then
            lastIndex = CurrentPage + 5
        Else
            lastIndex = 10
        End If
        If lastIndex > Convert.ToInt32(ViewState("TotalPages")) Then
            lastIndex = Convert.ToInt32(ViewState("TotalPages"))
            firstIndex = lastIndex - 10
        End If

        If firstIndex < 0 Then
            firstIndex = 0
        End If

        For i As Integer = firstIndex To lastIndex - 1
            Dim dr As DataRow = dt.NewRow()
            dr(0) = i
            dr(1) = i + 1
            dt.Rows.Add(dr)
        Next

        Me.dlPaging.DataSource = dt
        Me.dlPaging.DataBind()
    End Sub

    'dlPaging_ItemCommand set’s CurrentPage Property and again makes a call to BindItemsList().
    Protected Sub dlPaging_ItemCommand(ByVal source As Object, ByVal e As DataListCommandEventArgs)
        If e.CommandName.Equals("Paging") Then
            CurrentPage = Convert.ToInt16(e.CommandArgument.ToString())
            Me.BindItemsList()
        End If
    End Sub

    'dlPaging_ItemDataBound will set Enabled equals to false when binding the LinkButton which is currently clicked from paging list.
    Protected Sub dlPaging_ItemDataBound(ByVal sender As Object, ByVal e As DataListItemEventArgs)
        Dim lnkbtnPage As LinkButton = DirectCast(e.Item.FindControl("lnkbtnPaging"), LinkButton)
        If lnkbtnPage.CommandArgument.ToString() = CurrentPage.ToString() Then
            lnkbtnPage.Enabled = False
            lnkbtnPage.Style.Add("fone-size", "14px")

            lnkbtnPage.Font.Bold = True
        End If
    End Sub

    'Event Handlers for next, previous, first & last LinkButton’s.
    Protected Sub lbtnNext_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles lbtnNext.Click
        CurrentPage += 1
        Me.BindItemsList()
    End Sub
    Protected Sub lbtnPrevious_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles lbtnPrevious.Click
        CurrentPage -= 1
        Me.BindItemsList()
    End Sub
    Protected Sub lbtnLast_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles lbtnLast.Click
        CurrentPage = (Convert.ToInt32(ViewState("TotalPages")) - 1)
        Me.BindItemsList()
    End Sub
    Protected Sub lbtnFirst_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles lbtnFirst.Click
        CurrentPage = 0
        Me.BindItemsList()
    End Sub

End Class

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Bob Learned

I am confused about that "paging link" that you are referring to. Can you please point it out to me?

tjgrindsted

ASKER

'BindItemsList() calls doPaging() method which actually binds paging DataList.
    Private Sub doPaging()
        Dim dt As New DataTable()
        dt.Columns.Add("PageIndex")
        dt.Columns.Add("PageText")

        firstIndex = CurrentPage - 5

        If CurrentPage > 5 Then
            lastIndex = CurrentPage + 5
        Else
            lastIndex = 10
        End If
        If lastIndex > Convert.ToInt32(ViewState("TotalPages")) Then
            lastIndex = Convert.ToInt32(ViewState("TotalPages"))
            firstIndex = lastIndex - 10
        End If

        If firstIndex < 0 Then
            firstIndex = 0
        End If

        For i As Integer = firstIndex To lastIndex - 1
            Dim dr As DataRow = dt.NewRow()
            dr(0) = i
            dr(1) = i + 1
            dt.Rows.Add(dr)
        Next

        Me.dlPaging.DataSource = dt
        Me.dlPaging.DataBind()
    End Sub

    'dlPaging_ItemCommand set’s CurrentPage Property and again makes a call to BindItemsList().
    Protected Sub dlPaging_ItemCommand(ByVal source As Object, ByVal e As DataListCommandEventArgs)
        If e.CommandName.Equals("Paging") Then
            CurrentPage = Convert.ToInt16(e.CommandArgument.ToString())
            Me.BindItemsList()
        End If
    End Sub

    'dlPaging_ItemDataBound will set Enabled equals to false when binding the LinkButton which is currently clicked from paging list.
    Protected Sub dlPaging_ItemDataBound(ByVal sender As Object, ByVal e As DataListItemEventArgs)
        Dim lnkbtnPage As LinkButton = DirectCast(e.Item.FindControl("lnkbtnPaging"), LinkButton)
        If lnkbtnPage.CommandArgument.ToString() = CurrentPage.ToString() Then
            lnkbtnPage.Enabled = False
            lnkbtnPage.Style.Add("fone-size", "14px")

            lnkbtnPage.Font.Bold = True
        End If
    End Sub

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Bob Learned

Nope, that's too much detail...

Are you referring to "lnkbtnPage"?

tjgrindsted

ASKER

yes from the Protected Sub dlPaging_ItemDataBound i dont get the data from this sub so i get the numeric paginglink

Bob Learned

Did you stop data-binding on page post-back? You still need to bind to something, just not performing a full data retrieval every time.

tjgrindsted

ASKER

I dont know, Im new to this and trying to understand this "World" i do what im showing in code, I dont know is im stop data-binding on page or not.

If i add OnItemDataBound="dlPaging_ItemDataBound" to the dlPaging Datalist, then i get a
"NullReferenceException was unhandled by user code" for the codeline
If lnkbtnPage.CommandArgument.ToString() = CurrentPage.ToString() Then
in Protected Sub dlPaging_ItemDataBound.

tjgrindsted

ASKER

I dont know if im stop data-binding, but after adding this, i got it to work.

Main_Page

...
       <asp:DataList ID="dlPaging" runat="server" RepeatDirection="Horizontal" OnItemCommand="dlPaging_ItemCommand" OnItemDataBound="dlPaging_ItemDataBound">
                                    <ItemTemplate>
                                        <asp:LinkButton ID="lnkbtnPaging" runat="server" CommandArgument='<%# Eval("PageIndex") %>'
                                            CommandName="Paging" Text='<%# Eval("PageText") %>'></asp:LinkButton>&nbsp;
                                    </ItemTemplate>
                                    <SeparatorTemplate>&nbsp;|&nbsp;</SeparatorTemplate>
         </asp:DataList>
....

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Code_Behind

...
    'dlPaging_ItemDataBound will set Enabled equals to false when binding the LinkButton which is currently clicked from paging list.
    Protected Sub dlPaging_ItemDataBound(ByVal sender As Object, ByVal e As DataListItemEventArgs)
        If e.Item.ItemType <> ListItemType.Separator Then
            Dim lnkbtnPage As LinkButton = DirectCast(e.Item.FindControl("lnkbtnPaging"), LinkButton)
            If lnkbtnPage.CommandArgument.ToString() = CurrentPage.ToString() Then
                lnkbtnPage.Enabled = False
                lnkbtnPage.Style.Add("fone-size", "14px")
                lnkbtnPage.Font.Bold = True
            End If
        End If
    End Sub
...

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Can u say if i Stop the data-binding or not !?

Bob Learned

doPaging has these lines that bind data:

theDataList.DataSource = pagedData
theDataList.DataBind()

I would suggest this course of action:

1) Build a PagedDataSource on page load

2) Store the PagedDataSource in a Session variable, that is stored on the server per browser session

3) On page postback, get the PagedDataSource from the session variable, and bind to the DataList.

tjgrindsted

ASKER

do u have an ex. on this !?

ASKER CERTIFIED SOLUTION

Bob Learned

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tjgrindsted

ASKER

thx for the help.