MVVM with observalbe collection not updating series

[Rüdiger]

HI,
(must say that I am a SL and RadChart newbie)

1. I created a sample application, with one SL Toolkit chart and a RadChart on a page. I do it in what I believe is the usual SL way, by creating a ViewModel, which is INotyfy-able and contains an observable collection (of keyvalues). A timer in the viewmodel updates the collection every some seconds and fires the property-change event.
My ToolKit chart updates, the RadChart does not. What went wrong. I attach my code at the end.

2. My final goal is to create an interactive column chart: When a column is selected AndAlso the mouse-wheel is moved, then the value of the column is in/decremented. Quite simple. That is why I do the observable collection. My question is whether somebody already has such a scenario and could communicate this to me?

Thanks in advance,
RüdiActivity

3. The code:

<UserControl x:Class="TestSimpleViewModel.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:thisApp="clr-namespace:TestSimpleViewModel"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400" 
    xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" xmlns:toolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit">
    <UserControl.Resources>
        <thisApp:MySimpleViewModel x:Key="VM" />
    </UserControl.Resources>
 
    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.RowDefinitions>
            <RowDefinition Height="139*" />
            <RowDefinition Height="15" />
            <RowDefinition Height="146*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="17" />
            <ColumnDefinition Width="365*" />
            <ColumnDefinition Width="18" />
        </Grid.ColumnDefinitions>
        <telerik:RadChart Name="RadChart1" Grid.Column="1" />
        <toolkit:Chart Grid.Column="1" Grid.Row="2" Name="Chart1" Title="Chart Title">
            <toolkit:ColumnSeries Name="Executed" DependentValuePath="Value" IndependentValuePath="Key" ItemsSource="{Binding Source={StaticResource VM}, Path=HistoricalData}"></toolkit:ColumnSeries>
        </toolkit:Chart>
    </Grid>
</UserControl>







The ViewModel:

Imports System.ComponentModel
Imports System.Windows.Threading
Imports System.Collections.ObjectModel
 
Public Class MySimpleViewModel
    Implements INotifyPropertyChanged
 
    Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
    Public Property HistoricalData As ObservableCollection(Of KeyValuePair(Of DateTime, Double))
    Private WithEvents aTimer As New DispatcherTimer
 
    Public Sub New()
        Me.UpdateSeries()
        With aTimer
            .Interval = TimeSpan.FromMilliseconds(8000)
            .Start()
        End With
    End Sub
 
    Private Sub aTimer_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles aTimer.Tick
        Me.UpdateSeries()
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("HistoricalData"))
    End Sub
 
    Private Sub UpdateSeries()
        Me.HistoricalData = New ObservableCollection(Of KeyValuePair(Of DateTime, Double))
        Dim rnd As New Random
 
        Dim d As DateTime = Today
        For i = 1 To 24
            Me.HistoricalData.Add(New KeyValuePair(Of DateTime, Double)(d, rnd.Next(30, 100) + rnd.Next(0, 30)))
            d = d.AddDays(1)
        Next
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("HistoricalData"))
    End Sub

End Class


Code-behind:

Imports System.ComponentModel
Imports Telerik.Windows.Controls.Charting
 
Partial Public Class MainPage
    Inherits UserControl
 
    Private m_ViewModel As MySimpleViewModel
 
    Public Sub New()
        InitializeComponent()
 
        If Not DesignerProperties.IsInDesignTool Then
            m_ViewModel = New MySimpleViewModel
            Me.DataContext = m_ViewModel
 
            Dim seriesMapping As New SeriesMapping()
            seriesMapping.LegendLabel = "Product Sales"
            seriesMapping.SeriesDefinition = New SplineSeriesDefinition()
            seriesMapping.ItemMappings.Add(New ItemMapping("Key", DataPointMember.XValue))
            seriesMapping.ItemMappings.Add(New ItemMapping("Value", DataPointMember.YValue))
 
            Me.RadChart1.SeriesMappings.Add(seriesMapping)
            Me.RadChart1.ItemsSource = m_ViewModel.HistoricalData
        End If
    End Sub
End Class

[Yavor]

Hi Rüdiger,

Can you please confirm that you are using the latest version of the control?
This capability of the control was re-enabled in the latest version, so in case you are using an older version, this may be the cause of the problem. You can download the latest internal build, and give the setup a try. If the problem continues, you can open a formal support ticket, and send us a small working project, demonstrating the issue, for additional review and testing.

Regards,
Yavor
the Telerik team