What am I doing wrong with observable collection?

[David White]

XAML snippet for Form

    <chart:SfChart x:Name="Chart" HeightRequest="300" WidthRequest="200" >

      <chart:SfChart.PrimaryAxis>
        <chart:DateTimeAxis IntervalType="Days" >
          <chart:DateTimeAxis.LabelStyle>
            <chart:ChartAxisLabelStyle LabelFormat = "MM-dd-yy"></chart:ChartAxisLabelStyle>
          </chart:DateTimeAxis.LabelStyle>
        </chart:DateTimeAxis>
      </chart:SfChart.PrimaryAxis>

      <chart:SfChart.SecondaryAxis>
        <chart:NumericalAxis Maximum="0" Minimum="5" Interval="0.5">
        </chart:NumericalAxis>
      </chart:SfChart.SecondaryAxis>

      <chart:SfChart.Series>
        <chart:LineSeries ItemsSource ="{Binding Data}" XBindingPath="DateTimeStamp" YBindingPath="Score" Color="Red" />
      </chart:SfChart.Series>

    </chart:SfChart>  

Code in ViewModel:

        public ObservableCollection<StandardsFeedback> Data 
        {
            get;
            set;
        }

When I add or delete from this collection the chart does not update. Even if I trigger the OnPropertyChanged

[Divya Venkatesan]

Hi David,

We have done the sample to showcase adding or removing data from ObservableCollection. Please download the sample from following location.

Sample: http://www.syncfusion.com/downloads/support/forum/129905/ze/LineChart1741757198

Please get back to us if you are still facing issues in this.

Regards,
Divya Venkatesan

[David White]

Your sample app works fine. There is only one problem, it does not work with a ViewModel. In the MVVM framework I am using, updates to data are done in the ViewModel and then you notify through the  INotifyPropertyChanged interface. Instead of hooking to a Clicked event I put a Command in that resides in the ViewModel and then update data from there.

In the ViewModel

        public Command FirstTimeCommand { get; set; }

        private void FirstTime(object obj)
        {
                Data.Add(new StandardsFeedback(new DateTime(2016, 01, 07), 4));
        }

in the form

        <Button x:Name="button1" Text="Add" Command="{Binding FirstTime}"/>

[Divya Venkatesan]

Hi David,

We suspect that you are binding to FirstTime() instead of FirstTimeCommand property. We have also modified the sample and attached for your reference.

Sample: http://www.syncfusion.com/downloads/support/forum/129905/ze/LineChart754213584

Please get back to us if you need further assistance on this.

Regards,
Divya Venkatesan