How to trigger on bound item in WPF?

Question

I want to activate a trigger if the bound items property ID is equal to a property in my custom control.

But i can't use bindings in my triggers!

How would i do this?

Answer 1

DataTrigger's value property doesn't take bindings?

    <DataTrigger Binding="{Binding BoundPropertyId}" Value="{Binding ElementName=Mine, Path=Property}" />

If that doesn't work, you might need to hook onto an event and process it yourself in the code-behind.

Answer 2

This should work:

<DataTrigger
    Value="True">

    <DataTrigger.Binding>
        <MultiBinding
            Converter="{x:Static local:EqualityConverter.Instance}">
            <Binding
                Path="BoundProperty" />
            <Binding
                ElementName="MockCustomControl"
                Path="Text" />
        </MultiBinding>
    </DataTrigger.Binding>

    <DataTrigger.Setters>
        <Setter
            TargetName=" ... "
            Property=" ... "
            Value=" ... " />

         ...
         ...

    </DataTrigger.Setters>

</DataTrigger>

And the converter may be something similar to this:

public class EqualityConverter : IMultiValueConverter
{
    public static readonly EqualityConverter Instance = new EqualityConverter();

    #region IMultiValueConverter Members

    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (values == null || values.Length == 0) return false;

        for (int i = 1; i < values.Length; i++)
            if (!values[i].Equals(values[0])) return false;

        return true;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }

    #endregion
}

Note that I've used a generic convrter that can campare n values, but you can use a simple one as per your needs.

Hope this helps.