D
Don Miller
Here is an example of what I believe is a bug in ASP.NET 2.0 GridView paging
without postbacks (or at least not documented how to fix it). Once the
GridView is displayed, clicking on any of the paging tools causes the
GridView to completely disappear! This happens when either DataSets or
DataTables are used (it doesn't work at all for DataReaders because they
don't support paging apparently).
If you remove the EnableSortingAndPageCallbacks parameter from the script
below and add a PageIndexChanging sub, the paging works fine except there is
a postback for every page. I would prefer to NOT have a postback and instead
use the the AJAX-like callbacks when EnableSortingAndPageCallbacks is
enabled.
Protected Sub AuthorsGridView_PageIndexChanging(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles
AuthorsGridView.PageIndexChanging
AuthorsGridView.PageIndex = e.NewPageIndex
bindDataToGridView()
End Sub
So, how can you use GridView with callback paging without postbacks? What's
missing from the code and why shouldn't the code work? And where is the
documentation for avoiding this problem?
Thanks for any help.
<%@ Page language="VB" %>
<script runat="server">
Private Sub bindDataToGridView()
'This example uses Microsoft SQL Server and connects
Dim strSQL As String = "SELECT [au_fname], [au_lname], [city] FROM
[authors]"
Dim con As New
System.Data.SqlClient.SqlConnection("server=localhost;database=pubs;integrated
security=SSPI")
Dim cmd = New System.Data.SqlClient.SqlCommand(strSQL, con)
Dim ad As New System.Data.SqlClient.SqlDataAdapter(cmd)
Dim ds As New Data.DataSet
'Dim dt As New Data.DataTable
ad.Fill(ds)
'ad.Fill(dt)
AuthorsGridView.DataSource = ds
'AuthorsGridView.DataSource = dt
AuthorsGridView.DataBind()
End Sub
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
If Not IsPostBack Then
bindDataToGridView()
End If
End Sub
</script>
<html>
<body>
<form id="Form1" runat="server">
<h3>Disappearing GridView Example</h3>
<asp:gridview id="AuthorsGridView"
autogeneratecolumns="False"
AllowPaging="True"
EnableSortingAndPagingCallbacks="True"
PageSize="3"
runat="server" CellPadding="4" ForeColor="#333333" GridLines="None">
<Columns>
<asp:BoundField DataField="au_fname" HeaderText="First Name">
</asp:BoundField>
<asp:BoundField DataField="au_lname" HeaderText="Last Name">
</asp:BoundField>
<asp:BoundField DataField="City" HeaderText="City">
</asp:BoundField>
</Columns>
<RowStyle BackColor="#E3EAEB" />
<PagerStyle BackColor="#666666" ForeColor="White"
HorizontalAlign="Center" />
<HeaderStyle BackColor="#1C5E55" Font-Bold="True"
ForeColor="White" />
<AlternatingRowStyle BackColor="White" />
</asp:gridview>
</form>
</body>
</html>
without postbacks (or at least not documented how to fix it). Once the
GridView is displayed, clicking on any of the paging tools causes the
GridView to completely disappear! This happens when either DataSets or
DataTables are used (it doesn't work at all for DataReaders because they
don't support paging apparently).
If you remove the EnableSortingAndPageCallbacks parameter from the script
below and add a PageIndexChanging sub, the paging works fine except there is
a postback for every page. I would prefer to NOT have a postback and instead
use the the AJAX-like callbacks when EnableSortingAndPageCallbacks is
enabled.
Protected Sub AuthorsGridView_PageIndexChanging(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles
AuthorsGridView.PageIndexChanging
AuthorsGridView.PageIndex = e.NewPageIndex
bindDataToGridView()
End Sub
So, how can you use GridView with callback paging without postbacks? What's
missing from the code and why shouldn't the code work? And where is the
documentation for avoiding this problem?
Thanks for any help.
<%@ Page language="VB" %>
<script runat="server">
Private Sub bindDataToGridView()
'This example uses Microsoft SQL Server and connects
Dim strSQL As String = "SELECT [au_fname], [au_lname], [city] FROM
[authors]"
Dim con As New
System.Data.SqlClient.SqlConnection("server=localhost;database=pubs;integrated
security=SSPI")
Dim cmd = New System.Data.SqlClient.SqlCommand(strSQL, con)
Dim ad As New System.Data.SqlClient.SqlDataAdapter(cmd)
Dim ds As New Data.DataSet
'Dim dt As New Data.DataTable
ad.Fill(ds)
'ad.Fill(dt)
AuthorsGridView.DataSource = ds
'AuthorsGridView.DataSource = dt
AuthorsGridView.DataBind()
End Sub
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
If Not IsPostBack Then
bindDataToGridView()
End If
End Sub
</script>
<html>
<body>
<form id="Form1" runat="server">
<h3>Disappearing GridView Example</h3>
<asp:gridview id="AuthorsGridView"
autogeneratecolumns="False"
AllowPaging="True"
EnableSortingAndPagingCallbacks="True"
PageSize="3"
runat="server" CellPadding="4" ForeColor="#333333" GridLines="None">
<Columns>
<asp:BoundField DataField="au_fname" HeaderText="First Name">
</asp:BoundField>
<asp:BoundField DataField="au_lname" HeaderText="Last Name">
</asp:BoundField>
<asp:BoundField DataField="City" HeaderText="City">
</asp:BoundField>
</Columns>
<RowStyle BackColor="#E3EAEB" />
<PagerStyle BackColor="#666666" ForeColor="White"
HorizontalAlign="Center" />
<HeaderStyle BackColor="#1C5E55" Font-Bold="True"
ForeColor="White" />
<AlternatingRowStyle BackColor="White" />
</asp:gridview>
</form>
</body>
</html>