How Do I Switch ViewModel/View At runtime?

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WPF

MVVM

I know this subject has been beaten to death, but no example I have found explains exactly what I need. I created an example application that loads a view model via an ObservableCollection. The main window has a DataTemplate that links the view to it. All is well and good and it works fine. However, I need to switch the main window between entirely different ViewModels and their respective views arbitrary at runtime. I could add additional ViewModels to the ObservableCollection, but I have no idea how to switch between them. Any help would be appreciated.


Here are some code snippets:



App.xaml.cs

namespace HDI_WPF_MVVMIntro_cs
{
    /// <summary>
    /// Interaction logic for App.xaml
    /// </summary>
    public partial class App : Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            MainWindow window = new MainWindow();
            var viewModel = new MainWindowsViewModel();
            window.DataContext = viewModel;
            window.Show();
        }
    }
}

MainWindowViewModel.cs

using System.Collections.ObjectModel;
using HDI_WPF_MVVMIntro_cs.DataAccess;

namespace HDI_WPF_MVVMIntro_cs.ViewModel
{
    public class MainWindowsViewModel : ViewModelBase
    {
        readonly EmployeeRespository _employeeRepository;

        ObservableCollection<ViewModelBase> _viewModels;

        public MainWindowsViewModel()
        { 
            _employeeRepository = new EmployeeRespository();
            EmployeeListViewModel viewModel = new EmployeeListViewModel  (_employeeRepository);
            this.ViewModels.Add(viewModel);
        }

        public ObservableCollection<ViewModelBase> ViewModels
        {
            get
            {
                if (_viewModels == null)
                {
                    _viewModels = new ObservableCollection<ViewModelBase>();
                }

                return _viewModels;
            }
        }
    }
}

MainWindow.xaml

<Window x:Class="HDI_WPF_MVVMIntro_cs.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:HDI_WPF_MVVMIntro_cs.ViewModel"
        xmlns:vw="clr-namespace:HDI_WPF_MVVMIntro_cs.View"
        Title="MainWindow" Height="350" Width="525">
    
    <Window.Resources>
        <DataTemplate DataType="{x:Type vm:EmployeeListViewModel}">
            <vw:EmployeeListView />
        </DataTemplate>
    </Window.Resources>
    
    <Grid Margin="4">
        <ItemsControl ItemsSource="{Binding ViewModels}" Margin="4" />
    </Grid>
</Window>