显示带有DataContext的新窗口

Question

I want to simply display my UserControl in a separate window, for example by calling

var windowHandler = new WindowHandler();
windowHandler.Show(new SchoolViewModel);

How do I archive this? I have tried the following:

Set the DataTemplate in App.xaml:

<Application.Resources>
    <ResourceDictionary>
        <DataTemplate DataType="{x:Type viewModel:SchoolViewModel}">
            <view:SchoolUserControl />
        </DataTemplate>
    </ResourceDictionary>
</Application.Resources>

In code-behind call it:

private void Application_Startup(object sender, StartupEventArgs e)
{
    var windowHandler = new WindowHandler();
    windowHandler.ShowWindow(new SchoolViewModel(), 200, 200);
}

WindowHandler class:

public class WindowHandler
{
    public void ShowWindow(object dataContext, int height, int width)
    {
        Window window = new Window()
        {
            DataContext = dataContext,
            Width = width,
            Height = height
        };
        window.Show();
    }
}

It does show a window, but it's empty. Why is it empty? I also set the DataContext in the UserControl 's code-behind:

public SchoolUserControl()
{
    InitializeComponent();
    DataContext = this;
}

Answer 1

Window is by default templated to show Window.Content and not Window.DataContext . So you should assign whatever you want to show as content:

public class WindowHandler
{
    public void ShowWindow(object dataContext, int height, int width)
    {
        Window window = new Window()
        {
            Content = dataContext,
            Width = width,
            Height = height
        };
        window.Show();
    }
}

Also, as others noted, you should remove this line:

DataContext = this;

from your SchoolUserControl , because otherwise you won't have access to the templated view-model from within the control. And since SchoolUserControl is part of a DataTemplate , the templated view-model will be automatically available from SchoolUserControl.DataContext .