ultrawebgrid paging using LoadOnDemand as XML

Question

I have an ultrawebgrid with the paging enabled in it. As the data to be displayed is around 10K rows, pagination is carried out by setting the LoadOnDemand="XML" property.

The issue I'm facing is when I navigate through the pages, I could see an AJAX call happening but the data displayed is only of the first page.

For ex: I have 10 pages of data, when i click on page '3' the grid displays the content of page '1' itself.

But if I sort or filter any column, sorting and filtering results are as expected.

.aspx:

<DisplayLayout BorderCollapseDefault="Separate" Name="SampleGrid" RowHeightDefault="20px" SelectTypeRowDefault="Single" Version="4.00" AllowColSizingDefault="Free" SelectTypeColDefault="Single" TableLayout="Fixed" AllowAddNewDefault="Yes" AllowSortingDefault="OnClient" AllowUpdateDefault="Yes" AutoGenerateColumns="False" CellClickActionDefault="Edit" ViewType="Hierarchical">.

<Pager><PagerStyle CssClass="igwgPgrBlack2k7" /></Pager>

</DisplayLayout>

.vb:

Protected Sub SampleGrid_InitializeDataSource(ByVal sender As Object, ByVal e As Infragistics.WebUI.UltraWebGrid.UltraGridEventArgs) Handles SampleGrid.InitializeDataSource

Dim dsData As System.Data.DataSet

Dim sql As String

dsData = DataManager.ExecuteDataset(ConnectionType.XXX, Data.CommandType.Text, sql) // getting dataset


'Me.SampleGrid.DisplayLayout.Pager.PageCount = Math.Ceiling(dsData.Tables(0).Rows.Count/Me.SampleGrid.DisplayLayout.Pager.PageSize) //on first load, i'm getting the PageSize as 8 whereas it has to be 50 rows, I tried setting the page size in 'InitializeLayout' but 'InitializeDataSource' event is called first. So where do i set the grid's PageSize.


SampleGrid.DataSource = dsData
End Sub


Protected Sub SampleGrid_InitializeLayout(ByVal sender As Object, ByVal e As Infragistics.WebUI.UltraWebGrid.LayoutEventArgs) Handles SampleGrid.InitializeLayout

Dim htmlString As New StringBuilder

SampleGrid.Browser  = BrowserLevel.Xml

e.Layout.LoadOnDemand   = LoadOnDemand.Xml

e.Layout.RowsRange = 50

e.Layout.XmlLoadOnDemandType = XmlLoadOnDemandType.Accumulative

SampleGrid.DisplayLayout.Pager.StyleMode=PagerStyleMode.QuickPages

SampleGrid.DisplayLayout.EnableInternalRowsManagement=True 

SampleGrid.DisplayLayout.Pager.AllowCustomPaging=True 

SampleGrid.DisplayLayout.Pager.AllowPaging = True

SampleGrid.DisplayLayout.Pager.PageSize = 50

SampleGrid.DisplayLayout.Pager.QuickPages = 5

htmlString.Append("<table cellspacing='0' cellpadding='0' style='width:100%;border:solid 1px Black;'>")

htmlString.Append("<tr>")

htmlString.Append("<td width='25%' align='right'>Viewing page [currentpageindex] of [pagecount] </td>")

htmlString.Append("<td align='center'>")

htmlString.Append("<b>[page:1:First]&nbsp;[prev]</b>")

htmlString.Append("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;")

htmlString.Append("[default]")

htmlString.Append("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;")

htmlString.Append("<b>[next]&nbsp;[page:[pagecount]:Last]</b>")

htmlString.Append("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;")

htmlString.Append("</td>")

htmlString.Append("<td width='25%' align='left' title='Enter page number and press Enter'>")

htmlString.Append("Go to:<input id='PagerGotoPageNumber' size='5' style='vertical-align:text-bottom;height:20px;font-family:verdana;font-size:8pt;padding:0 0 0 0;border:solid 1px black' onkeydown='return gotoPageKeyDown();' type='text' autocomplete='off' />")

htmlString.Append("<button style='height:22px' onclick='gotoPage();'>Go</button>")

htmlString.Append("</td>")

htmlString.Append("</tr>")

htmlString.Append("</table>")

SampleGrid.DisplayLayout.Pager.Pattern=htmlString.ToString()

End Sub


Private Sub SampleGrid_PageIndexChanged(ByVal sender As System.Object, ByVal e As Infragistics.WebUI.UltraWebGrid.PageEventArgs) Handles SampleGrid.PageIndexChanged

        SampleGrid.DisplayLayout.Pager.CurrentPageIndex = e.NewPageIndex

    End Sub

Answer 1

With custom paging it is expected that you will provide the data for the page that you are looking to load. This is necessary because your custom paging may be implemented to have letters rather than page numbers like the example in the Infragistics help.

If you are looking to do this you would need to make the following changes:

• The PageIndexChanged event should be removed.
• The dataset that you are binding to should only have the elements for the specific page. Note that this will also have an impact on sorting and filtering and may prevent them from working unless you return filtered and/or sorted results.

A simple example that shows paging working with the code that you are using is:

Protected Sub UltraWebGrid1_InitializeDataSource(sender As Object, e As Infragistics.WebUI.UltraWebGrid.DataSourceEventArgs) Handles UltraWebGrid1.InitializeDataSource        
    Me.UltraWebGrid1.DisplayLayout.Pager.PageCount = 4

    Me.UltraWebGrid1.DataSource = Me.GetEmployees(Me.UltraWebGrid1.DisplayLayout.Pager.CurrentPageIndex)
End Sub

    Private Function GetEmployees(page As Integer) As DataTable
    Dim dtData As DataTable = New DataTable("Employees")

    dtData.Columns.Add("EmployeeID", GetType(Integer))
    dtData.Columns.Add("Name", GetType(String))
    dtData.Columns.Add("OnSite", GetType(Boolean))
    dtData.Columns.Add("DateOfHire", GetType(DateTime))
    dtData.Columns.Add("Department", GetType(Integer))

    For i As Integer = (page - 1) * 50 To (page - 1) * 50 + 50 Step 1
        dtData.Rows.Add(New Object() {i, String.Format("Name {0}", i), (i Mod 2 = 0), DateTime.Today, i Mod 8})
    Next

    Return dtData
End Function

'Protected Sub UltraWebGrid1_PageIndexChanged(sender As Object, e As Infragistics.WebUI.UltraWebGrid.PageEventArgs) Handles UltraWebGrid1.PageIndexChanged
'    Me.UltraWebGrid1.DisplayLayout.Pager.CurrentPageIndex = e.NewPageIndex
'End Sub

Note that you may not need to use custom paging, if you set DisplayLayout.AllowCustomPaging to false then the grid would handle the paging automatically when you click the first,prev, numbers, next and last options in the pager. This would also allow you to keep your data as is and not have to also manually handle sorting and filtering. If you do this you would still remove the PageIndexChanged handler.

Note that then for the go to button after the input, you would likely need to set the page in JavaScript which can be done with the goToPage client side method of the WebGrid.

While it isn't related to the issue that you are having, setting EnableInternalRowsManagement to true has no affect when using InitializeDataSource to set the DataSource of the WebGrid.