New Post: Custom WF Activity with a custom List object bound to CollectionControl

Hello,

This question needs someone familiar with the CollectionControl as well as Workflow.

I'm building a WF Activity which simply executes a stored procedure. The Activity is associated with a WPF Designer that contains the WFT Toolkit CollectionControl. Everything looks fine and dandy, except I am trying to bind the CollectionControl to an InArgument of the Activity.

The WF Activity has a property of
public InArgument<List<System.Data.SqlClient.SqlParameter>> Parameters { get; set; }

I want to edit this InArgument using the CollectionControl on the designer, and in fact the CollectionControl itself seems to work fine. I have written a custom converter to try to get the Items from the CollectionControl and bind them to the InArgument of the Activity, but it doesn't seem to work. I can't get the collection from the CollectionControl and get it over to the InArgument.

The question: I want to edit the list of SqlParameters using the CollectionControl (which seems to work fine in the designer), but how can I get those SqlParameters to be persisted over to the Activity Property?

Much Thanks!

Activity.cs
The Activity defines an InArgument that wants a list of SqlParameters
public class MyCustomActivity: CodeActivity

{
    public InArgument<List<SqlParameter>> Parameters { get; set; }

    protected override void Execute(CodeActivityContext context)
    {
        //stuff
    }
}

Activity Designer Xaml
In the activity designer, the CollectionControl is bound to the ItemsSource, over to the Parameters property of the activity.
<sap:ActivityDesigner.Resources>

<ResourceDictionary>
        <converters:CollectionEditorToSqlParameterListConverter x:Key="sqlParametersConverter"/>
    </ResourceDictionary>
</sap:ActivityDesigner.Resources>
<Grid Margin="0,0,0,-162">
    <xctk:CollectionControl x:Name="SprocParameters" HorizontalAlignment="Left" Margin="0,28,0,10" Width="668"
             IsReadOnly="True" ItemsSource="{Binding Path=ModelItem.Parameters, Mode=TwoWay, Converter={StaticResource sqlParametersConverter}}"/>
</Grid>

Converter

//Convert from the activity properties to the designer element

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var modelItem = value as ModelItem;
        if (modelItem != null)
        {
            var inArgument = modelItem.GetCurrentValue() as InArgument<string>;
            if (inArgument != null)
            {
                var expression = inArgument.Expression;
                var literal = expression as Literal<string>;
                var csexpression = expression as CSharpValue<string>;
                if (literal != null)
                    return literal.Value;
            }
        }
        return null;
    }

    //Convert from the designer element to the activity property
    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var itemContent = (string)value;
        var csArgument = new Literal<string>(itemContent);
        var inArgument = new InArgument<string>(csArgument);
        return inArgument;
    }