Editing an Uri object

Hello!

I would like to know if somebody has edited a property of Uri type. In my application, I have a CLR-class which has a property named MyUri of type Uri.

 
My property grid is:

                <ms:PropertyGrid Name="_properties" SelectedObject="{Binding}" >
                    <ms:PropertyGrid.Editors>
                        <ms:TypeEditor EditedType="{x:Type sys:Uri}" EditorTemplate="{StaticResource UriEditor}" />
                    </ms:PropertyGrid.Editors>
                </ms:PropertyGrid>

 and the template for UriEditor:

<local:UriConverter x:Key="UriConverter" /> 

<DataTemplate x:Key="UriEditor">
<ms:TextBox Text="{Binding Mode=TwoWay, Path=MyUri, Converter={StaticResource UriConverter}" />
</DataTemplate>
 

and the UriConverter code is:

    class UriConverter : IValueConverter
    {
        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value.AbsolutePath;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            string source = value.ToString();
            Uri uri = null;
            try
            {
                uri = new Uri(source);
            }
            catch { }
            return uri;
        }

        #endregion
    }
 

It doesn't work when I write an existing filename in DataTemplate's TextBox. But, when I put my ms:TextBox in a Window, like a simple control, it works! I.e., it doesn't work when TextBox is inside the grid.

Any help?

Thanks. 

Hello Josep,

The reason this is not working is that your DataTemplate is receiving a Uri object and is trying to bind to the MyUri property of that object.  A TypeEditor on a reference type passes the referenced object, so that the template can bind directly to the properties of that object; see the PhoneNumber example in the Editors sample and note how the text boxes bind to the CountryCode, etc. properties.

Instead, you need to use a PropertyEditor.  A PropertyEditor allows you to reference the entire passed object as if it were a property called Value:

<DataTemplate x:Key="UriEditor">
  <ms:TextBox Text="{Binding Value, Converter={StaticResource UriConverter}}" />
 </DataTemplate>

<ms:PropertyEditor DeclaringType="..." PropertyName="MyUri" EditorTemplate="{StaticResource UriEditor}" />

If you have lots of properties of type Uri, and/or don't want to name the properties explicitly, you'll need to get a recent nightly build.  TypeEditor now has a TemplateBindingMode property.  By setting TemplateBindingMode="WrappedValue" then you can get the PropertyEditor-style behaviour in a TypeEditor, which is useful for immutable reference types like Uri.

(If you don't like using nightlies, you can get the same effect in the RTM version, but you'll have to write a smart editor declaration -- see http://www.mindscape.co.nz/blog/index.php/2008/04/30/smart-editor-declarations-in-the-wpf-property-grid/ for details.)