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On RadGrid CustomPaging and FilteringByColumn working together

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Lorenzo
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Lorenzo asked on 27 Jul 2012, 09:05 AM
Hi,
I'm looking for a very urgent clarification about the concurrency of CustomPaging and FilteringByColumn used together in a RadGrid.
I always have as a datasource a function that returns a DataTable considering both Filtering and Paging. This is necessary since the amount of datas is very significative and cannot return the whole amount of datas to the RadGrid and the Page it, but I have to return only the needed records and only in small paged size (50 records).

The approach I've used up to now is as illustrated here:
Default.aspx
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<head runat="server">
    <title></title>
    <telerik:RadStyleSheetManager id="RadStyleSheetManager1" runat="server" />
</head>
<body>
    <form id="form1" runat="server">
    <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
        <Scripts>
            <%--Needed for JavaScript IntelliSense in VS2010--%>
            <%--For VS2008 replace RadScriptManager with ScriptManager--%>
            <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.Core.js" />
            <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.jQuery.js" />
            <asp:ScriptReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Common.jQueryInclude.js" />
        </Scripts>
    </telerik:RadScriptManager>
    <script type="text/javascript">
        //Put your JavaScript code here.
    </script>
    <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
    </telerik:RadAjaxManager>
    <div>
 
        <telerik:RadGrid runat="server" ID="RadGrid" AutoGenerateColumns="false" AllowCustomPaging="true" AllowPaging="true" PageSize="50"
        AllowFilteringByColumn="true" EnableLinqExpressions="false">
         
        <GroupingSettings CaseSensitive="False" />
             
            <ClientSettings>
                <Selecting AllowRowSelect="True" />
                <Scrolling AllowScroll="True" ScrollHeight="100%" UseStaticHeaders="True" />
            </ClientSettings>
 
            <PagerStyle AlwaysVisible="True" />
 
            <MasterTableView OverrideDataSourceControlSorting="True">
             
                <NoRecordsTemplate>
                      
                </NoRecordsTemplate>
             
                <Columns>
 
                <%--Some columns here--%>
 
                </Columns>
 
            </MasterTableView>
         
        </telerik:RadGrid>
    </div>
    </form>
</body>
</html>
  
Default.aspx.vb
Imports Telerik.Web.UI
Imports System.Data
 
Partial Class _Default
    Inherits System.Web.UI.Page
 
 
    Protected Sub RadGrid_NeedDataSource(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGrid.NeedDataSource
 
         
        Dim VirtualItemCount As Integer = GetDatasVirtualItemsCount(RadGrid.MasterTableView.FilterExpression)
 
        RadGrid.MasterTableView.VirtualItemCount = VirtualItemCount
        RadGrid.VirtualItemCount = VirtualItemCount
 
 
        Dim startIndex As Integer = IIf((ShouldApplySortFilterOrGroup()), 0, RadGrid.CurrentPageIndex * RadGrid.PageSize)
        Dim pageSize As Integer = IIf((ShouldApplySortFilterOrGroup()), VirtualItemCount, RadGrid.PageSize)
 
 
        RadGrid.DataSource = GetDatas(startIndex, pageSize, RadGrid.MasterTableView.FilterExpression)
 
    End Sub
 
    Private isGrouping As Boolean = False
    Protected Sub RadGrid1_GroupsChanging(ByVal source As Object, ByVal e As GridGroupsChangingEventArgs)
        isGrouping = True
        If e.Action = GridGroupsChangingAction.Ungroup AndAlso RadGrid.CurrentPageIndex > 0 Then
            isGrouping = False
        End If
    End Sub
 
    Public Function ShouldApplySortFilterOrGroup() As Boolean
        Return RadGrid.MasterTableView.FilterExpression <> "" _
        OrElse (RadGrid.MasterTableView.GroupByExpressions.Count > 0 OrElse isGrouping) OrElse RadGrid.MasterTableView.SortExpressions.Count > 0
    End Function
 
    Private Function GetDatas(ByVal startIndex As Integer, ByVal pageSize As Integer, ByVal FilterExpression As String) As DataTable
 
        ' ------------
        ' Some Code that generates a datatable considering both CustomPaging and Filtering
        ' ------------
 
        Return New DataTable
 
    End Function
 
    Private Function GetDatasVirtualItemsCount(ByVal FilterExpression As String) As Integer
 
        ' ------------
        ' Some Code that count the number of rows considering Filtering
        ' ------------
 
        Return -1
 
    End Function
 
End Class

This works fine, but if I use Filtering then Paging gets disabled ! Now I need to use both together so my approach in the code behind has simply changed this way:
Imports Telerik.Web.UI
Imports System.Data
 
Partial Class _Default2
    Inherits System.Web.UI.Page
 
 
    Protected Sub RadGrid_NeedDataSource(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGrid.NeedDataSource
 
 
        Dim VirtualItemCount As Integer = GetDatasVirtualItemsCount(RadGrid.MasterTableView.FilterExpression)
 
        RadGrid.MasterTableView.VirtualItemCount = VirtualItemCount
        RadGrid.VirtualItemCount = VirtualItemCount
 
 
        Dim startIndex As Integer = RadGrid.CurrentPageIndex * RadGrid.PageSize
        Dim pageSize As Integer = RadGrid.PageSize
 
 
        RadGrid.DataSource = GetDatas(startIndex, pageSize, RadGrid.MasterTableView.FilterExpression)
 
    End Sub
 
    Private Function GetDatas(ByVal startIndex As Integer, ByVal pageSize As Integer, ByVal FilterExpression As String) As DataTable
 
        ' ------------
        ' Some Code that generates a datatable considering both CustomPaging and Filtering
        ' ------------
 
        Return New DataTable
 
    End Function
 
    Private Function GetDatasVirtualItemsCount(ByVal FilterExpression As String) As Integer
 
        ' ------------
        ' Some Code that count the number of rows considering Filtering
        ' ------------
 
        Return -1
 
    End Function
 
End Class

The only thing changed is the approach in retrieving the startIndex and the pageSize that now works the same way either if I'm filtering or not.

My point is: this thing seems to work, but I have to deliver it very soon and since I have not found posts of this approach anywhere I'm wondering if I'm missing something important that this approach does not consider.

If anybody finds reasonable reasons why this should fail in some circumstances please let me know.  

Thanks in advance.

Lorenzo

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Tsvetina
Telerik team
answered on 01 Aug 2012, 07:48 AM
Hi Lorenzo,

I reviewed your code and according to your description, the approach seems correct to me. In case you notice any problems in the grid behavior in the future, feel free to contact us through the support system and let us know.

All the best,
Tsvetina
the Telerik team
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Tsvetina
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