Compare Objects in XAML using a generic IValueConverter

Here is a way for XAM Designers to compare two instances inside XAML using an IValueConverter. Imagine that you have a ComboBox and few other controls. ComboBox is bounded to a Collection of objects (In my attached code I am binding it to an Enum). In such a situation the UI designer wants to enable/disable some other controls based on the selected value of the ComboBox. He can use the following IValueConnverter class as a Generic comparer which will return a true or false.

public class GenericComparer : IValueConverter
{
object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value == null) return false;

// If the object has implemented IComparable
if (value is IComparable)
{
if (((IComparable)value).CompareTo(parameter) == 0)
return true;
}
else if (value.Equals(parameter))
return true;


return false;
}

Now instantiate a comparer in the resource as follows.

………………


If we wanted to control the IsEnabled property of a text box the XAML will be like


See the attached source code for details.



Comments

Anonymous said…
Interesting to know.
Tuesday, November 11, 2008 at 5:11:00 AM PST
Anonymous said…
Thats interesting. Couldnt find many examples on how to use the "parameter" parameter of the Convert.
Wednesday, April 29, 2009 at 10:43:00 PM PDT
Indian said…
wanted to download the code and registrations are disabled :(

could you please help?
Monday, February 22, 2010 at 6:36:00 AM PST
Michael Tang said…
Lovely blog, thanks for taking the time to share this
Tuesday, January 9, 2024 at 4:05:00 PM PST
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