WPF binding update notification for nested property when parent property changes

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I have a ViewModel with a complex property type and want to bind my view to a nested property of this object.

My ViewModel is implementing INotifyPropertyChanged (or do be extact BaseViewModel is implementing it). The class of the parent property is not implementing INotifyPropertyChanged.

When I'm updating the value of the parent property, the nested property is not updating. Can you tell me how can I implement this functionality?

ViewModel

public class ViewModel : BaseViewModel
{
    private Car _myCarProperty;

    public Car MyCarProperty
    {
        get { return _myCarProperty; }
        set
        {
            if (value == _myCarProperty) return;

            _myCarProperty = value;
            OnPropertyChanged();
        }
    }
}

Binding in the View

<TextBlock Text="{Binding Path=MyCarProperty.Manufacturer}" />

When I change the value of MyCarProperty the View does not update.

Thanks for any help!

Edit: OnPropertyChanged() implementation

#region INotifyPropertyChanged

public event PropertyChangedEventHandler PropertyChanged;

[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChangedEventHandler handler = PropertyChanged;
    if (handler != null)
    {
        handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

#endregion INotifyPropertyChanged

"The class Car is not implementing INotifyPropertyChanged. But I'm not changing the property Manufacturer, I change the MyCarProperty property, and so I expect that the OnNotifyPropertyChanged event will trigger the value update?"

Nope, it won't trigger the value update a level down. Bindings don't listen to property changes for an entire path, they listen only to the object that they're bound to.

I see a couple options off the top of my head (in order of my preference when I run into this):

  1. Bind to the car, not the sub property, and create a data template that displays what you want out of it.
  2. Manually kick the binding by calling UpdateTarget on it's BindingExpression when you need to.

I know it looks like there's a lot more to learn on the data template route, but I promise you that data templates will prove vastly more powerful, scalable, maintainable, and useful than manually kicking bindings as you work more in WPF. (Also, once you understand them, I think they're actually less work than manually kicking bindings).

Good luck!

Parent property name with nested properties not updating in UI for , When I change one of that property I fire PropertyChanged but ToString() never calling again and I see old name of parent property on GUI. The accepted answer explains how to handle the case where a sub-property on a Binding Source is changed and you wish to update the view - which is not what the question is asking. WPF will in fact respond to changes from many levels down, so long as you are notifying changes for any properties being changed within the specified path. As for this:

The accepted answer explains how to handle the case where a sub-property on a Binding Source is changed and you wish to update the view - which is not what the question is asking. WPF will in fact respond to changes from many levels down, so long as you are notifying changes for any properties being changed within the specified path.

As for this:

"The class Car is not implementing INotifyPropertyChanged. But I'm not changing the property Manufacturer, I change the MyCarProperty property, and so I expect that the OnNotifyPropertyChanged event will trigger the value update?"

WPF handles this already.

In your example, ViewModel is the Binding Source. When you set MyCarProperty (firing the NotifyPropertyChanged event), WPF will re-evaluate the Binding Target Value using the Binding Path for the new Binding Source object - updating your view with the new Manufacturer.

I have tested this with a simple WPF app - it also holds true for very deeply nested Paths:

https://pastebin.com/K2Ct4F0F

<!-- When MyViewModel notifies that "MyCarProperty" has changed, -->
<!-- this binding updates the view by traversing the given Path -->
<TextBlock Text="{Binding Path=MyCarProperty.Model.SuperNested[any][thing][you][want][to][try][and][access].Name}" />

https://social.msdn.microsoft.com/Forums/vstudio/e, NET Framework since the beginning, data binding became more prominent with the advent of Windows Presentation Foundation (WPF) and XAML, as it forms the The object should raise this event when a bindable property changes, in order to notify the view that it should refresh its representation of the property's value. WPF binding update notification for nested property when parent property changes. I have a ViewModel with a complex property type and want to bind my view to a nested property of this object. My ViewModel is implementing INotifyPropertyChanged (or do be extact BaseViewModel is implementing it).

I'm not an WPF expert, but I think it's because you've chosen the wrong path.

<TextBlock Text="{Binding Path=MyCarProperty, Value=Manufacturer}" />

update:

<TextBlock Text="{Binding Source=MyCarProperty, Path=Manufacturer}" />

Data Binding, WPF Binding Update Notification for a nested property when a parent property changes I have a ViewModel with a complex property type and want to bi This example shows how to set up to be notified when the binding target (target) or the binding source (source) property of a binding has been updated. Windows Presentation Foundation (WPF) raises a data update event each time that the binding source or target has been updated.

WPF binding update notification for an attached property when a , Because XAML/MVVM/Binding has been around in the common place for If you update Street , you're not raising any property changed events, the only You don't have to raise a notification for every property up the food chain. be my preferred option (sending the event to the parent binded model). To support OneWay or TwoWay binding to enable your binding target properties to automatically reflect the dynamic changes of the binding source (for example, to have the preview pane updated automatically when the user edits a form), your class needs to provide the proper property changed notifications.

Binding to a model inside a model, Jun 01, 2019 · In WPF, in order for the changes in the class property to reflect in on Parent property name with nested properties not updating of UI for WPF to notify the view or ViewModel that it does not matter which property is binding;  New binding: <Label Content="{Binding Path=Model.Name}"/> After changing value of property Name of Model object, the binding automatically refresh (because Model impl. INPC). b) ViewModel, exposes Name (as in your example) Property Changing of the model will not lead to binding automatically refresh (because binding source ViewModel but not Model) – Memoizer Jan 29 '13 at 17:08

Onpropertychanged wpf, This Unit data type property has it's own child properties. could raise PropertyChanged notifications for a parent property when it's In fact, most WPF controls don't require that the root property raises the to nested object properties, you can create a property changed callback: We will update it soon. This topic (at least when you add Part One and the upcoming Part Two together) is a summation of various different property-changed notification mechanisms that are part of WPF, and will attempt to describe the design intentions, and also how these design intentions might influence your choices about how to report property changes if you are defining custom properties and objects.

Comments
  • have you notify child property?
  • The class Car is not implementing INotifyPropertyChanged. But I'm not changing the property Manufacturer, I change the MyCarProperty property, and so I expect that the OnNotifyPropertyChanged event will trigger the value update? - please see my edited question.
  • Can you show us how OnPropertyChanged is implemented?
  • I added the OnPropertyChanged implementation.
  • @FelixC Is your BaseViewModel telling the compiler it's implementing INotifyPropertyChanged, e.g. public class BasseViewModel: INotifyPropertyChanged? Your example seemed to work when I did a little mock up.
  • Thanks Greg! I know about data templates and should not have any problems with them. I had the same issue some time ago and I remember that I found something in the past that sounds like "deep looking bindings", but I guess it was only the VeryObservableCollection I found here - which does not help with this issue. I hoped that something similiar would be existing. But the data template idea is perfect :)
  • Sorry, what? WPF doesn't listen to changes along the path? I wish I knew this before I started using chained paths everywhere. Hey, stop. It works! ;)
  • @Greg D, the "data template" link is outdated. Sorry, i just feel bored.
  • Bored indeed! Updated with what I presume was the original link. :)
  • According to this there is no value attribute.
  • By the way: The Binding is working, just value updates are not propagated.