How to instantiate DataContext object in XAML

Question

I want to be able to create an instance of the DataContext object for my WPF StartupUri window in XAML, as opposed to creating it code and then setting the

Answer 1

Assuming this code:

public abstract class BaseView { }
public class RuntimeView : BaseView { }
public class DesigntimeView : BaseView { }

Try this:

<Page.DataContext>
    <local:RuntimeView />
</Page.DataContext>
<d:Page.DataContext>
    <local:DesigntimeView />
</d:Page.DataContext>
<ListBox ItemsSource="{Binding}" />

Best of luck!

Answer 2

If you need to set the DataContext as same control class:

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

use RelativeSource binding.

or just

     <Window x:Class="TabControl.MainWindow"
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        
                xmlns:local="clr-namespace:TabControl"
                Title="MainWindow" Height="350" Width="525"                        
                >
<Window.DataContext>
< new instance of any viewModel here....>
</Window.DataContext>
    </Window>

If want to assign an instance of different class than itself.

Answer 3

You add an XML namespace for whatever namespace your DataContext lives in, create an instance of it in the Window Resources and set the DataContext to that resource:

<Window x:Class="WpfApplication4.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication4"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <local:MyViewModel x:Key="MyViewModel"/>
    </Window.Resources>
    <Grid DataContext="{StaticResource MyViewModel}">

    </Grid>
</Window>

Answer 4

You can just specify this directly in XAML for the entire Window:

<Window 
    ... xmlns definitions ...
>
   <Window.DataContext>
        <local:CustomViewModel />
   </Window.DataContext>
</Window>

This creates a view model named "CustomViewModel" in the namespace aliased to local, directly as the DataContext for the Window.