Question

In my XAML code, I have a binding to the current dataitem like this:

Background="{Binding Path=., Converter={StaticResource ResourceKey=kBackground}}"

My converter uses several properties of the dataitem to determine the background. When any of those properties change, the background color could change. I want to send a notification to the target so that the background will change appropriately. My question is that I don’t know how to send such a notification when the binding path is “.”.

If my converter uses PropertyA and PropertyB, calling:

PropertyChanged(this, new PropertyChangedEventArgs("PropertyA"))

and/or

PropertyChanged(this, new PropertyChangedEventArgs("PropertyB"))

doesn’t trigger the binding. I tried calling this:

PropertyChanged(this, new PropertyChangedEventArgs("."))

but it didn’t trigger the binding either.

How do I call PropertyChanged in such a way that my “Path=.” bindings get notifications that they need to update?

This may be a duplicate question, but I couldn’t find one. I don’t know the terminology very well.

Answer 1

Try using an IMultiValueConverter instead, and passing it the properties it needs

<Grid.Background>
    <MultiBinding Converter="{StaticResource MyMultiValueConverter}">
        <Binding Path="PropertyA"/>
        <Binding Path="PropertyB"/>
    </MultiBinding>
</Grid.Background>

This should get re-evaluated anytime a PropertyChange notification is raised for either PropertyA or PropertyB

The alternative using your current binding syntax would be to raise a PropertyChange notification of your parent data item anytime PropertyA or PropertyB changes.

For example, assuming your current data item is SomeObject:

SomeObject.PropertyChanged += SomeObject_PropertyChanged;

...

void SomeObject_PropertyChanged(object src, PropertyChangedEventArgs e)
{
    if (e.PropertyName == "PropertyA" || e.PropertyName == "PropertyB")
    {
        RaisePropertyChanged("SomeObject");
    }
}