Updating Values for Certain Property Types in PropertyGrid

Hello,

Thank you for the sample.  I noticed that in your TestVM class, you are updating the field values for your properties in all their getters, which is not good for MVVM.  You also don't update the property values in the setters.  If you update the field value of the property, you have to raise the INotifyPropertyChanged.PropertyChanged event or PropertyGrid will not know when to update its UI.

Instead of this:

public int IntProperty {
    get => intValue++;
    set => OnPropertyChanged(nameof(IntProperty));
}

Your properties should look like this:

public int IntProperty {
    get => intValue;
    set {
        intValue = value;
        OnPropertyChanged(nameof(IntProperty));
    }
}

If you do that for each property and then use this kind of code for your button, everything works great:

private void Button_Click(object sender, RoutedEventArgs e) {
    TestDataObject.BoolProperty = !TestDataObject.BoolProperty;
    TestDataObject.IntProperty++;
}

Alright, this VM works, but in my actual case, what’s triggered by the button here doesn’t modify the properties—I want it to invalidate them so they get refreshed, just like it currently works with the bool. Do you know why it behaves this way with bool natively but not with other types?

Hello,

I looked at the sample project again and apologize that I missed where in CustomPropertyModel you were calling:

NotifyPropertyChanged(nameof(Value));

That is why a couple of the value editors updated.  The other value editors bind their UI to "ValueAsString" instead of "Value".  If you add this, then they all update:

NotifyPropertyChanged(nameof(ValueAsString));

However I would suggest that you replace both those lines in your EventTriggerer_EventTriggered event handler with this single line instead, which ends up doing both of those along with other things like updating any child properties, etc.

Refresh(PropertyRefreshReason.ValueChanged);

In general, it's often better to design the view models to be properly observable where the getter does not modify the value, and the setter does and raises INotifyPropertyChanged.PropertyChanged.  But if you have a case here where that typical observable design doesn't work, then using that Refresh call will do what you need.

Hello,

Thanks, that’s exactly what I was looking for! I tried to implement a truly observable VM, but as you mentioned, I found that in my case it I prefer this approach.

Thanks again,
Benjamin.