绑定到父DataContext的资源

Question

I want to have access to parent DataContext in resource to use it in binding. Here is sample:

<Window x:Class="WpfApplication44.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:l="clr-namespace:WpfApplication44"
    x:Name="MyWindows"
    Title="MainWindow"
    Width="525"
    Height="350"
    DataContext="{Binding RelativeSource={RelativeSource Self}}">

<Window.Resources>
    <l:SomeResource x:Key="SomeResource">
        <l:SomeResource.Context>
            <!--
                DataContext is set to windows object.
                I want to bind to window`s title property
            -->
            <Binding Path="Title" />
        </l:SomeResource.Context>
    </l:SomeResource>
</Window.Resources>

<StackPanel>
    <Label>
        <StaticResource ResourceKey="SomeResource" />
    </Label>

    <!--  UPD  -->
    <TextBlock Text="{Binding Source={StaticResource SomeResource}, Path=Context}" />
</StackPanel>

But I get:

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=Title; DataItem=null; target element is 'SomeResource' (HashCode=25557385); target property is 'Context' (type 'Object')

SomeResource is derived from DependencyObject and contains only one dependency property Context of type object.

It looks like resources don't have access to parent's DataContext property and it is not set event if resource is of type FrameworkElement. I've tried to use ElementName, RelativeSource in my binding but with no luck.

All I need is to set parent's DataContext to resources. I'm using MVVM so any MVVM solutions are preferable.

UPD Link to project is here

Answer 1

Oh it looks like a DataProxy than modify your SomeResource to Freezable like this:

public class SomeResource : Freezable
{
    protected override Freezable CreateInstanceCore()
    {
        return new SomeResource();
    }

    public static readonly DependencyProperty ContextProperty = DependencyProperty.Register("Context", typeof(object), typeof(SomeResource), new PropertyMetadata(default(object)));

    public object Context
    {
        get { return (object)GetValue(ContextProperty); }
        set { SetValue(ContextProperty, value); }
    }
}