Binding a subclass property

Question

In WindowViewModel There is a property called statusBar

In StatusBarViewModel , There is a property called public BatteryIndicatorViewModel batIndicatorViewModel

In BatteryIndicatorViewModel , There is a property called public bool IsLowBattery

<MultiDataTrigger.Conditions>
<Condition Binding="{Binding statusBar.batIndicatorViewModel.IsLowBattery}" Value="true" />
 </MultiDataTrigger.Conditions>

IsLowBattery property is bound to CheckBox, in window2 and which is bound to WindowViewModel

<CheckBox IsChecked="{Binding Path=statusBar.batIndicatorViewModel.IsLowBattery}" Content="Low Battery" Grid.Column="2" Margin="0,0,34.743,14.04" Grid.Row="1" />

It shows the following error:- System.Windows.Data Error: 39 : BindingExpression path error: 'statusBar' property not found on 'object' ''StatusBarViewModel' (HashCode=25431989)'. BindingExpression:Path=statusBar.batIndicatorViewModel.IsLowBattery; DataItem='StatusBarViewModel' (HashCode=25431989); target element is 'ContentControl' (Name=''); target property is 'NoTarget' (type 'Object')

---

Code.....

Window2.xaml.. I have a HeaderedItemsControl in Window2.xaml which is bound to workspaces

<Grid>
<HeaderedItemsControl ItemsSource="{Binding Path=Workspaces}" Header="StatusBar" />
<CheckBox IsChecked="{Binding statusBar.batIndicatorViewModel.IsLowBattery}" Content="Low Battery" Grid.Column="2" Margin="0,0,34.743,14.04" Grid.Row="1" />
<CheckBox IsChecked="{Binding statusBar.batIndicatorViewModel.IsCharging}" Content="Charging" Grid.Column="1" Grid.ColumnSpan="2" Height="15.96" Margin="5.76,0,48.67,0" Grid.Row="2" VerticalAlignment="Top" />
</Grid>

WindowViewModel.cs..

WindowViewModel which is bound to window2 datacontext

public class WindowViewModel:WorkspaceViewModel
{
public ObservableCollection<WorkspaceViewModel> Workspaces        

    public StatusBarViewModel StatusBarVM;

    private void ShowStatusBar()
            {            
                StatusBarVM = new StatusBarViewModel();
                this.Workspaces.Add(StatusBarVM);
                this.SetActiveWorkspace(StatusBarVM);            
            }

StatusBar.xaml..

<usercontrol>
<Grid Background="Black" Height="20" Width="240">
<vw:BatteryIndicator Height="20" Width="30" IsTabStop="False" VerticalAlignment="Top" HorizontalAlignment="Right" Grid.Column="1"/>
<!—some other usercontrols are used here -- >
</Grid>
</UserControl>

StatusBarViewModel.cs..

public class StatusBarViewModel : WorkspaceViewModel
    {
public BatteryIndicatorViewModel BatteryIndicatorVM;
}

BatteryIndicatorViewModel.cs..

public class BatteryIndicatorViewModel : WorkspaceViewModel
    {
Public  bool IsCharging;
public bool IsLowBattery;
}

Now my question is how do I bind IsCharging in BatteryIndicatorViewModel to low battery checkbox in windowviewmodel

Answer 1

The error is telling you that the DataContext of the element where the Binding is being used is already set to a StatusBarViewModel, most likely the statusBar property. You should be able to remove the "statusBar." from the beginning of your Binding Path and get what you're looking for.