Questions on UI for WPF Forum

6 answers

124 views

Hi,

We are currently having issues running our application on Windows 7 tablet PC's. When the grid has data, we get a NullReferenceException. I found it that the exception will not occur when removing a specific column definition from the gridview:

<telerik:GridViewColumn     CellTemplate="{StaticResource StatusButtons}"
                                            IsFilterable="False"
                                            MaxWidth="120"
                                            MinWidth="120"
                                            />

The application works fine on non-touch devices, but on touch devices (Win 7, .Net 3.5) the error occurs. Stopping the "Tablet PC Input" service does not help as mentioned in other threads.

The exception plus stacktrace

2012-01-09 10:09:18,868 FATAL - User Interface : Unhandled Exception

System.NullReferenceException: De objectverwijzing is niet op een exemplaar van een object ingesteld.

bij System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()

bij System.Windows.Automation.Peers.AutomationPeer.UpdateChildren()

bij System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()

bij System.Windows.ContextLayoutManager.fireAutomationEvents()

bij System.Windows.ContextLayoutManager.UpdateLayout()

bij System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)

bij System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork()

bij System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()

bij System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)

bij System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)

bij System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)

bij System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)

The Xaml:

<UserControl x:Class="BrabantWater.UI.Screens.ZInspectionListScreen"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:lex="http://schemas.root-project.org/xaml/presentation"

xmlns:imageFactory="clr-namespace:Sap.Eam.UI.Theme;assembly=CustomTheme_WPF"

xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

Height="auto" Width="auto">

<UserControl.Resources>

<BooleanToVisibilityConverter x:Key="boolToVisConverter"/>

<DataTemplate x:Key="StatusButtons">

<StackPanel Orientation="Horizontal" Width="110">

<telerik:RadButton Click="RadButtonDelete_Click" MinWidth="50"

IsEnabled="{Binding Path=IsDeletable, Mode=OneWay}">

<Image Source="{Binding Path=DeleteImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

<telerik:RadButton Click="RadButtonStatus_Click" MinWidth="50"

IsEnabled="{Binding Path=IsEditable,Mode=OneWay}">

<Image Source="{Binding Path=StatusImage, Mode=OneWay}" Width="32"/>

</telerik:RadButton>

</StackPanel>

</DataTemplate>

</UserControl.Resources>

<Grid x:Name="GridContainer">

<Grid.RowDefinitions>

<RowDefinition Height="auto"/>

<RowDefinition Height="*"/>

</Grid.RowDefinitions>

<StackPanel Grid.Row="0" Orientation="Horizontal" Margin="5,5,5,5" Height="35" HorizontalAlignment="Stretch" VerticalAlignment="Center">

<telerik:RadButton x:Name="ButtonNewInstallation" Content="{lex:LocText Key=Inspection_New_Installation, Dict=InspectionResources, Assembly=Win32Resources}" MinWidth="100" Click="ButtonNewInstallation_Click"/>

<telerik:RadButton x:Name="ButtonNewDamage" Content="{lex:LocText Key=Inspection_New_Defect, Dict=InspectionResources, Assembly=Win32Resources}" Margin="10,0,0,0" MinWidth="100" Click="ButtonNewDamage_Click"/>

</StackPanel>

<telerik:RadGridView x:Name="InspectionGrid"

AlternationCount="2"

AutoGenerateColumns="False"

CanUserFreezeColumns="False"

CanUserReorderColumns="False"

ColumnWidth="*"

EditTriggers="None"

Grid.Row="1"

Margin="5"

MouseDoubleClick="InspectionGrid_MouseDoubleClick"

RowIndicatorVisibility="Collapsed"

SelectionChanged="InspectionGrid_SelectionChanged"

SelectedItem="{Binding Path=CurrentInspection, Mode=TwoWay}"

ShowGroupPanel="false">

<telerik:RadGridView.Columns>

<telerik:GridViewDataColumn UniqueName="DamageCodeDescription"

Header="{lex:LocText Key=Inspection_Space, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=DamageCodeDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="ItemCodeDescription"

Header="{lex:LocText Key=Inspection_Part, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ItemCodeDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="ItemDescription"

Header="{lex:LocText Key=Inspection_Addition, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ItemDescription, Mode=OneWay}"/>

<telerik:GridViewDataColumn UniqueName="CauseCodeDescription"

Header="{lex:LocText Key=Inspection_Task, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=CauseCodeDescription, Mode=OneWay}" />

<telerik:GridViewDataColumn UniqueName="TaskCodeDescription"

Header="{lex:LocText Key=Inspection_Finding, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=TaskCodeDescription, Mode=OneWay}" />

<telerik:GridViewDataColumn UniqueName="ActivityCodeDescription"

Header="{lex:LocText Key=Inspection_Risk, Dict=InspectionResources, Assembly=Win32Resources}"

DataMemberBinding="{Binding Path=ActivityCodeDescription, Mode=OneWay}" />

<telerik:GridViewImageColumn DataMemberBinding="{Binding Path=AttachmentImage, Mode=OneWay}"

Header="{lex:LocText Key=Inspection_Attachments, Dict=InspectionResources, Assembly=Win32Resources}"

ImageHeight="32"

ImageWidth="32"

IsFilterable="False"

MaxWidth="60"

MinWidth="60"

/>

<telerik:GridViewColumn CellTemplate="{StaticResource StatusButtons}"

IsFilterable="False"

MaxWidth="120"

MinWidth="120"

/>

</telerik:RadGridView.Columns>

</telerik:RadGridView>

</Grid>

</UserControl>

The version of the Telerik WPF components being used: 2010.2.0716.35.

How can we solve this issue?

Kind regards,

Mike

GridView

answered on 11 Jan 2012

5 answers

91 views

A few questions

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Is this possible?

Also, are there any samples on how to use this in an MVVM scenario using QueryableEntityCollection<T> in the viewmodel?

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how i can return the current row when RadComboBox is changed, and how i get the contorls inside the row as well.

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.ASPX

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

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

</telerik:RadScriptManager>

<div>

<telerik:RadGrid runat="server" AllowPaging="True" ID="RadGrid2" OnNeedDataSource="RadGrid2_NeedDataSource" Width="600px" PageSize="8">

<MasterTableView Width="100%" >

<Columns>

<telerik:GridBoundColumn HeaderText="Project Name" DataField="name" ></telerik:GridBoundColumn>

</Columns>

<NoRecordsTemplate>

<div style="height: 30px; cursor: pointer;">

No items to view</div>

</NoRecordsTemplate>

<PagerStyle Mode="NumericPages" PageButtonCount="4" />

</MasterTableView>

</telerik:RadGrid>

</div>

</form>

ASPX.VB

Imports System

Imports System.Collections.Generic

Imports System.Configuration

Imports System.Data

Imports System.Data.Common

Imports System.Data.SqlClient

Imports System.Web.UI

Imports Telerik.Web.UI

Public Class bookmarks

Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

End Sub

Protected Sub RadGrid2_NeedDataSource(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGrid2.NeedDataSource

RadGrid2.DataSource = getBookMarks

End Sub

Private ReadOnly Property getBookMarks() As IList(Of project)

Get

Dim strSQL As String = "SELECT PROJ_NAME FROM [OPI_TIMESHEETS] o left outer join DCSC_PROJECT d on o.project_number = d.PROJ_NO "

Dim results As IList(Of project) = New List(Of project)()

Using connection As IDbConnection = DbProviderFactories.GetFactory("System.Data.SqlClient").CreateConnection()

connection.ConnectionString = ConfigurationManager.ConnectionStrings("projcentral").ConnectionString

Using command As IDbCommand = connection.CreateCommand()

command.CommandText = strSQL

connection.Open()

Try

Dim reader As IDataReader = command.ExecuteReader()

While reader.Read()

Dim name As String = reader.GetValue(reader.GetOrdinal("PROJ_NAME"))

results.Add(New project(name))

End While

Catch ex As SqlException

results.Clear()

'lblmsg.Text = ex.Message

End Try

End Using

lblMsg.Text = results.Count & " items in list"

Return results

End Get

End Property

Class project

Private _projName As String

Sub New(ByVal name As String)

_projName = name

End Sub

#Region "properties"

Private ReadOnly Property Name() As String

Get

Return _projName

End Get

End Property

#End Region

End Class

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reference attached file.

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Can this be accomplished by simply sub-classing GridViewSelectColumn or GridViewDataColumn? Or can I set the cell header style to be bound somehow?

I'm just looking for a simpler implementation than what I've seen already.

Thank you.

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