在'System.Windows.StaticResourceExtension 上提供价值

Question

Inside a XAML Page I'm trying to use an IValueConverter , it's throwing an error.

• The IValueConverter is in another assembly, I have added a reference
• There are no design-time errors
• I have assigned the StaticResource with a ResourceKey

At the top of my page I have this:

xmlns:converters="clr-namespace:Converters;assembly=Converters"

<Page.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="Styles/DialogStyles.xaml" />
        </ResourceDictionary.MergedDictionaries>
        <converters:NoWhiteSpaceConverter x:Key="NoWhiteSpaceConverter" />
    </ResourceDictionary>
</Page.Resources>

Then I try to use it later on like this:

<TextBox Text="{Binding SomeText, Converter={StaticResource NoWhiteSpaceConverter}}" />

Can anyone see what the problem is?

Answer 1

Make sure that the resources are defined before the usage (in Xaml parsing order). The easiest way is to place it into App.xaml

See also here for a similar issue: http://www.paulkiddie.com/2011/10/the-importance-of-the-position-of-window-resources-element-in-wpf-xaml-markup/

Answer 2

In my case the resource was correctly defined before it is used but there was a wrong reference to a converter.

The problematic line was

...{Binding MyProperty, Converter={StaticResource local:MyConverter}}

and it should be without the namespace alias

...{Binding MyProperty, Converter={StaticResource MyConverter}}

where local is a namespace alias containig the converter class and MyConverter is the key defined in a resource in the XAML.