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Sorting on individual columns based on the same DataField value.

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Grid

This is a migrated thread and some comments may be shown as answers.

Tom asked on 04 Nov 2011, 04:44 PM

sorting.png

I have a RadGrid bound to a query result. One of the query fields is an Id value which I use as the DataField value in several GridBoundColumn columns. I've overriden GridBoundColumn.FormatDataValue so I can use the Id to look up an object in a session state collection. Depending on the column's HeaderText value, FormatDataValue returns different properties of the retrieved object.

This all works lovely, except sorting is based on the Id value, not on what's actually in the grid. Furthermore, the UI indicates that all the Id-based columns are the same, presumably because they have the same DataField value. In the attached screenshot, I clicked on the City column. I would expect Chicago to sort ahead of London and Washington, but the rows are sorted by Address Id and the UI shows all the Address Id-based columns as currently sorted.

How can I revise things to make sorting work as I would expect?

Code to reproduce the problem follows.

Please note: I'm not looking for an answer that says, "flatten your data before putting it in the grid." I understand that I could do that. Remember this is a trivial example of a much more complex application. I do not want to avoid the issue I've presented; I want to solve it.

Thank you kindly!

ASPX code:

<%@ Page Language="VB" %>

<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

<%@ Register TagPrefix="xx" Namespace="Example" %>

<%@ Import Namespace="System.Linq" %>

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

<script runat="server">

Protected Sub grdExample_NeedDataSource(ByVal sender As Object, ByVal e As GridNeedDataSourceEventArgs)

Dim Landmarks() As Landmark

Landmarks = {New Landmark With {.Name = "Wrigley Field", .AddressId = 3}, _

New Landmark With {.Name = "British PM Residence", .AddressId = 1}, _

New Landmark With {.Name = "Hofbräuhaus", .AddressId = 4}, _

New Landmark With {.Name = "Whitehouse", .AddressId = 2}}

grdExample.DataSource = Landmarks

End Sub

Protected Sub Page_Init(ByVal sender As Object, ByVal e As EventArgs)

If CType(Session.Item("addrCollection"), Address()) Is Nothing Then

Call Session.Add("addrCollection", _

{New Address With {.Id = 1, .Street = "10 Downing St", .City = "London", .PostalCode = "SW1A 2AA", .Province = "England", .Country = "UK"}, _

New Address With {.Id = 2, .Street = "1600 Pennsylvania Ave NW", .City = "Washington", .PostalCode = "20500", .Province = "District of Columbia", .Country = "USA"}, _

New Address With {.Id = 3, .Street = "1060 W. Addison St", .City = "Chicago", .PostalCode = "60613", .Province = "Illinois", .Country = "USA"}, _

New Address With {.Id = 4, .Street = "Am Platzl 9", .City = "Munich", .PostalCode = "D-80331", .Province = "Bavaria", .Country = "Germany"}})

End If

End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<title>Sorting Issue</title>

</head>

<body>

<form id="form1" runat="server">

<telerik:RadScriptManager ID="RadScriptManager1" runat="server" />

<div>

<telerik:RadGrid ID="grdExample" runat="server" OnNeedDataSource="grdExample_NeedDataSource" AllowSorting="true" AutoGenerateColumns="false" >

<MasterTableView>

<Columns>

<telerik:GridBoundColumn DataField="Name" HeaderText="Landmark" />

<telerik:GridNumericColumn DataField="AddressId" HeaderText="Address ID" />

<xx:SampleColumn DataField="AddressId" HeaderText="Country" />

<xx:SampleColumn DataField="AddressId" HeaderText ="Province" />

<xx:SampleColumn DataField="AddressId" HeaderText="City" />

<xx:SampleColumn DataField="AddressId" HeaderText="Street Address" />

<xx:SampleColumn DataField="AddressId" HeaderText="Postal Code" />

</Columns>

</MasterTableView>

</telerik:RadGrid>

</div>

</form>

</body>

</html>

Classes:

Option Infer Off

Option Strict On

Option Explicit On

Imports Telerik.Web.UI

Imports System.Web.HttpContext

Namespace Example

Public Class SampleColumn

Inherits GridBoundColumn

Protected Overrides Function FormatDataValue(ByVal dataValue As Object, ByVal item As GridItem) As String

Dim lm As Landmark

Dim Addresses As IEnumerable(Of Address)

Dim address As Address

lm = CType(item.DataItem, Landmark)

Addresses = CType(Current.Session.Item("addrCollection"), Address())

address = Addresses.First(Function(a As Address) a.Id = lm.AddressId)

Select Case MyBase.HeaderText

Case "Street Address"

Return address.Street

Case "City"

Return address.City

Case "Postal Code"

Return address.PostalCode

Case "Province"

Return address.Province

Case "Country"

Return address.Country

Case Else

Return "Huh?"

End Select

End Function

End Class

End Namespace

Public Class Landmark

Public Property Name As String

Public Property AddressId As Integer

End Class

Public Class Address

Public Property Id As Integer

Public Property Street As String

Public Property City As String

Public Property Province As String

Public Property PostalCode As String

Public Property Country As String

End Class

2 Answers, 1 is accepted

answered on 09 Nov 2011, 01:42 PM

Hi Tom,

The built-in sorting for the Grid works with the DataField property of the column. It executes the sorting query against the actual datasource for the grid, and not the visible display format of the data. One way to solve this is to use custom sorting, handle the SortingCommand yourself and there pass the sorted datasource of the grid, this way the data will be displayed in the desired way. More information on custom sorting can be found in this help article.

Kind regards,
Marin
the Telerik team

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