Bind to a method in WPF?

Question

How do you bind to an objects method in this scenario in WPF?

public class RootObject {     public string Name { get; }      public ObservableCollection<ChildObject> GetChildren() {...} }  public class ChildObject {     public string Name { get; } } 

XAML:

<TreeView ItemsSource="some list of RootObjects">     <TreeView.Resources>         <HierarchicalDataTemplate DataType="{x:Type data:RootObject}"                                    ItemsSource="???">             <TextBlock Text="{Binding Path=Name}" />         </HierarchicalDataTemplate>         <HierarchicalDataTemplate DataType="{x:Type data:ChildObject}">             <TextBlock Text="{Binding Path=Name}" />         </HierarchicalDataTemplate>     </TreeView.Resources> </TreeView> 

Here I want to bind to the GetChildren method on each RootObject of the tree.

EDIT Binding to an ObjectDataProvider doesn't seem to work because I'm binding to a list of items, and the ObjectDataProvider needs either a static method, or it creates it's own instance and uses that.

For example, using Matt's answer I get:

System.Windows.Data Error: 33 : ObjectDataProvider cannot create object; Type='RootObject'; Error='Wrong parameters for constructor.'

System.Windows.Data Error: 34 : ObjectDataProvider: Failure trying to invoke method on type; Method='GetChildren'; Type='RootObject'; Error='The specified member cannot be invoked on target.' TargetException:'System.Reflection.TargetException: Non-static method requires a target.

Answer 1

Another approach that might work for you is to create a custom IValueConverter that takes a method name as a parameter, so that it would be used like this:

ItemsSource="{Binding      Converter={StaticResource MethodToValueConverter},     ConverterParameter='GetChildren'}" 

This converter would find and invoke the method using reflection. This requires the method to not have any arguments.

Here's an example of such a converter's source:

public sealed class MethodToValueConverter : IValueConverter {     public object Convert(object value, Type targetType, object parameter, CultureInfo culture)     {         var methodName = parameter as string;         if (value==null || methodName==null)             return value;         var methodInfo = value.GetType().GetMethod(methodName, new Type[0]);         if (methodInfo==null)             return value;         return methodInfo.Invoke(value, new object[0]);     }      public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)     {         throw new NotSupportedException("MethodToValueConverter can only be used for one way conversion.");     } } 

And a corresponding unit test:

[Test] public void Convert() {     var converter = new MethodToValueConverter();     Assert.AreEqual("1234", converter.Convert(1234, typeof(string), "ToString", null));     Assert.AreEqual("ABCD", converter.Convert(" ABCD ", typeof(string), "Trim", null));      Assert.IsNull(converter.Convert(null, typeof(string), "ToString", null));      Assert.AreEqual("Pineapple", converter.Convert("Pineapple", typeof(string), "InvalidMethodName", null)); } 

Note that this converter does not enforce the targetType parameter.