Combobox Column Clearselection

[Scott Rakestraw]

Does the combobox column support the clearselection button that the radcombobox has?

[Pavel Pavlov]

Hello Scott ,

Unfortunately the GridVIewComboBoxColumn does not support  this functionality. It is intended for more general cases and when a specific requirement about the ComboBox editor occurs there is another approach needed  - redefine the CellEditTemplate of the column thus placing your editor with all the settings and additional logic.

Regards,
Pavel Pavlov
the Telerik team

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[Scott Rakestraw]

I have created a custom combo column to handle the clear selection, virtualized items and custom itemtemplates.  This is working great except for one problem which is that with the VirtualizingStackPanel when I go to the cell it does not automatically browse to the selected item.

Imports Telerik.Windows.Controls
Imports System.Windows.Data
Imports System.Windows
Imports System.Collections
Imports System.Windows.Markup

Public Class GridViewCustomComboBoxColumn
    Inherits GridViewComboBoxColumn

    Private _ItemTemplate As DataTemplate

    Public Property ItemTemplate() As DataTemplate
        Get
            Return _ItemTemplate
        End Get
        Set(ByVal Value As DataTemplate)
            _ItemTemplate = Value
        End Set
    End Property

    Public Overrides Function CreateCellElement(ByVal cell As Telerik.Windows.Controls.GridView.GridViewCell, ByVal dataItem As Object) As System.Windows.FrameworkElement

        If ItemTemplate Is Nothing Then

            Return Nothing

        Else

            Dim value As Object = dataItem.GetType.GetProperty(Me.DataMemberBinding.Path.Path).GetValue(dataItem, Nothing)

            Dim cellTemplate As FrameworkElement = CType(ItemTemplate.LoadContent, FrameworkElement)
            cellTemplate.DataContext = (From i In ItemsSource _
                                        Where i.GetType.GetProperty(SelectedValueMemberPath).GetValue(i, Nothing).Equals(value) _
                                        Select i).FirstOrDefault
            Return cellTemplate

        End If

    End Function

    Public Overrides Function CreateCellEditElement(ByVal cell As Telerik.Windows.Controls.GridView.GridViewCell, ByVal dataItem As Object) As System.Windows.FrameworkElement

        Dim cellEditElement As RadComboBox = CType(MyBase.CreateCellEditElement(cell, dataItem), RadComboBox)

        cellEditElement.ClearSelectionButtonVisibility = Windows.Visibility.Visible
        cellEditElement.ClearSelectionButtonContent = "Clear Selection"

        If Not ItemTemplate Is Nothing Then
            cellEditElement.DisplayMemberPath = Nothing
            cellEditElement.ItemTemplate = ItemTemplate
        End If

        If CType(ItemsSource, IList).Count > 100 Then
            Dim itemsPanelTemplate As New ItemsPanelTemplate
            itemsPanelTemplate = CType(XamlReader.Load("<ItemsPanelTemplate xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""><VirtualizingStackPanel /></ItemsPanelTemplate>"), ItemsPanelTemplate)
            cellEditElement.ItemsPanel = itemsPanelTemplate
        End If

        Return cellEditElement

    End Function

End Class

[Pavel Pavlov]

Hi Scott ,
It looks like quite an elegant solution. Can you please paste me the item template XAML. I am pretty sure we can find a solution for the selected value related problem

Regards,
Pavel Pavlov
the Telerik team

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[Scott Rakestraw]

In the one list that I have that is currently big enough to require the VirtualizingStackPanel it does not have an itemtemplate.  It is just a standard combobox with the VirtualizingStackPanel added.

[Pavel Pavlov]

Hi Scott ,
I have prepared a small project to try reproduce the problem ( please find it attached) .

However I was not able to find any disturbing behavior of the combo with the virtualizing panel. Am I missing something ?

Regards,
Pavel

[Scott Rakestraw]

The sample isn't using the virtualizing panel because it has < 100 records.  Make the following change.

    Private Function GetCountries() As List(Of Country)
        Dim countries As New List(Of Country)()
        For x As Integer = 1 To 1000
            countries.Add(New Country(x, InlineAssignHelper(Name, "Test " + x.ToString)))
        Next
        Return countries
    End Function

Select a record in the list then leave that cell and go back to it.  The value will still be correct but it will not autoscoll to that selected item in the list and will just show the first few items.

[Nedyalko Nikolov]

Hello Scott Rakestraw,

This issue is fixed with the latest internal build assemblies. I'm attaching the same test application for a reference.

Best wishes,
Nedyalko Nikolov
the Telerik team

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[Louis Bouchard]

And now in 2011, it's supported?

[ham]

Hi

This topic help me a lot in developing my project. I will contribute more when I finished it.

If you want to get more materials that related to this topic, you can visit: Project management templates

 

Best regards.