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I have a ViewModel without View

See original GitHub issue

I am using Caliburn.Micro to build WPF PC program, which is a great framework. But recently I have a problem: 　I have a ViewModel that does not require a View. It’s actually a navigation, through the TabControl Items switch to the specified website. 　I have browsed: View.cs, ConventionManager.cs, ViewLocator, ViewModelLocator, can not solve my distress. Can not find view for … always exists. 　Can I only create an empty view to solve this problem? Or can Caliburn.Micro provide such a switch to let me control?

AppBootstrapper：

namespace Caliburn.Micro.Test.WPF
{
  using System;
  using System.IO;
  using System.Windows;
  using System.Collections.Generic;
  using System.ComponentModel.Composition;
  using System.ComponentModel.Composition.Hosting;
  using System.ComponentModel.Composition.Primitives;
  using System.Linq;
  using Caliburn.Micro;

  public class AppBootstrapper : BootstrapperBase
  {

     private CompositionContainer container;

    public AppBootstrapper()
    {
        Initialize();
    }

    protected override void Configure()
    {
        var catalog = new AggregateCatalog(AssemblySource.Instance.Select(x => new AssemblyCatalog(x)).OfType<ComposablePartCatalog>());
        var batch = new CompositionBatch();
        var path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "plugins");

        if (!Directory.Exists(path))
            Directory.CreateDirectory(path);

        catalog.Catalogs.Add(new DirectoryCatalog(path));
        container = new CompositionContainer(catalog);

        batch.AddExportedValue(container);
        batch.AddExportedValue<IWindowManager>(new WindowManager());

        batch.AddExportedValue<IEventAggregator>(new EventAggregator());
        batch.AddExportedValue(catalog);

        container.Compose(batch);
    }

    protected override void BuildUp(object instance)
    {
        base.BuildUp(instance);
    }

    protected override object GetInstance(Type service, string key)
    {
        var contract = string.IsNullOrEmpty(key) ? AttributedModelServices.GetContractName(service) : key;
        var exports = this.container.GetExportedValues<object>(contract);

        if (exports.Any())
        {
            return exports.First();
        }

        throw new Exception(string.Format("Could not locate any instances of contract {0}.", contract));
    }

    protected override IEnumerable<object> GetAllInstances(Type service)
    {
        return this.container.GetExportedValues<object>(AttributedModelServices.GetContractName(service));
    }

    protected override void OnStartup(object sender, StartupEventArgs e)
    {
        DisplayRootViewFor<IShell>();
    }
}

}

ShellViewModel `

namespace Caliburn.Micro.Test.WPF.ViewModels
{
  using System;
  using System.Collections.Generic;
  using System.ComponentModel.Composition;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;

  [Export(typeof(IShell))]
  internal class ShellViewModel : Conductor<INavigation>.Collection.OneActive, IShell
  {
      [ImportingConstructor]
      public ShellViewModel([ImportMany]IEnumerable<INavigation> tabs)
      {
          Items.AddRange(tabs.OrderBy(x => x.Index));
          DisplayName = "WPF.Test";
      }
     
      public void NavigationChanged(SelectionChangedEventArgs e)
      {
        var tab = e.OriginalSource as TabControl;
        var nav = tab.SelectedItem as INavigation;
  
        if (nav == null)
            return;

        tab.SelectedIndex = nav.Redirect((e.RemovedItems[0] as INavigation).Index);
      }
  }
}

ShellView

<TabControl Name="Items" cal:Message.Attach="[Event SelectionChanged] = [Action NavigationChanged($eventArgs)]" />

INavigation `

public interface INavigation
{
    string Icon { get; set; }

    int Index { get; set; }

    int Redirect(int index);
}

BuyProductViewModel `

namespace Caliburn.Micro.Test.WPF.ViewModels
{
    [Export(typeof(INavigation))]
    internal class BuyProducts : Screen, INavigation
    {
        public string Icon { get; set; }

        public int Index { get; set; }

        public int Redirect(int index)
        {
           // System.Diagnostics.Process.Start("https://www.google.com/?p=BuyProduct");
            return Index;
        }

      public BuyProducts()
      {
          DisplayName = "Buy Product";
          Index = 0;
      }
  }
}

MoreProductsViewModel `

namespace Caliburn.Micro.Test.WPF.ViewModels
{
    [Export(typeof(INavigation))]
    internal class MoreProducts: Screen, INavigation
    {
        public string Icon { get; set; }

        public int Index { get; set; }

        public int Redirect(int index)
        {
           // System.Diagnostics.Process.Start("https://www.google.com/?p=More Products");
            return Index;
        }

      public MoreProducts()
      {
          DisplayName = "More Products";
          Index = 0;
      }
  }
}