Setting the DataContext to the current code-behind object in XAML

Question

I'm trying to set the DataContext for my UserControl to the code-behind class of the UserControl. It's really easy to do from the code-behind side:

public partial class OHMDataPage : UserControl
{
    public StringList Stuff { get; set; }

    public OHMDataPage ()
    {
        InitializeComponent();

        DataContext = this;
    }
}

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage">

    <ScrollViewer>
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

But how can I do this purely from the XAML side and at the UserControl level? It works on child nodes if I do this (and remove DataContext = this; from the code-behind):

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage">

    <ScrollViewer
        DataContext="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}">
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

I'd really like to understand how to do this on the UserControl itself. I expected this to work:

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="LCDHardwareMonitor.Pages.OHMDataPage"
    DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}">

    <ScrollViewer>
        <ListBox ItemsSource="{Binding Stuff}" />
    </ScrollViewer>

</UserControl>

but it doesn't.

Answer 1

DataContext="{Binding Mode=OneWay, RelativeSource={RelativeSource Self}}"

Should work.

But if your properties are not set before InitializeComponent() is called, the WPF binding mechanism doesn't know that your property's values are changed.

To give you a quick idea:

// the binding should work
public StringList Stuff { get; set; }
public Constructor()
{
    Stuff = new StringList { "blah", "blah", "foo", "bar" };
    InitializeComponent();
}

// the binding won't work
public StringList Stuff { get; set; }
public Constructor()
{
    InitializeComponent();
    Stuff = new StringList { "blah", "blah", "foo", "bar" };
}

If you're using a list of strings, consider using an ObservableCollection instead. This will notify the WPF binding mechanism when items are added or removed.