10 May 2007

Improvements for the SortableBindingList (and TypedList)

I found out that the sorting didn’t work for ‘Expression’ properties. My first thought was to add another switch to the logic of the already existing code

object value1 = t1;
object value2 = t2;

if (prop.Name.StartsWith("||"))
{
	// do something to find the 'ExpressionProperty' values
}
else
{
	foreach (string property in prop.Name.Split('.'))
	{
		// navigate through the relations
		PropertyInfo propertyInfo = value1.GetType().GetProperty(property);
		value1 = propertyInfo.GetValue(value1, null);
		value2 = propertyInfo.GetValue(value2, null);
	}
}

Since i already have a PropertyDescriptor it seems a lot smarter to use it’s GetValue instead

object value1 = prop.GetValue(t1);
object value2 = prop.GetValue(t2);

At Matthieu MEZIL’s blog i found a suggestion to use Comparer. This allowed me to reduce

IComparable comparable = value1 as IComparable;
if (comparable != null)
{
	return reverse * comparable.CompareTo(value2);
}
else
{
	comparable = value2 as IComparable;
	if (comparable != null)
	{
		return -1 \* reverse \* comparable.CompareTo(value1);
	}
	else
	{
		return 0;
	}
}

with

// Notice that this requires that atleast value1 or value2 are an instance of a type that implements IComparable
return reverse * Comparer.Default.Compare(value1, value2);

Feel free to get yet another version of TypedList.zip.

Tim Van Wassenhove

Improvements for the SortableBindingList (and TypedList)