NullReferenceException on DisplayRootViewFor <>

Question

NullReferenceException on DisplayRootViewFor <>

I created a class derived from BootstrapperBase

, overwritten OnStartup()

and called DisplayRootViewFor<AppViewModel>()

just like in the documentation.

But when I run the application, I get NullReferenceException

onDisplayRooViewFor<AppViewModel>()

using Caliburn.Micro;
using MHBRestore.Logic;
using MHBRestore.UI.ViewModel;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace MHBRestore.UI
{
public class AppBootstrapper : BootstrapperBase
{
    private SimpleContainer _container = new SimpleContainer();

    public AppBootstrapper()
    {
        Initialize();
    }

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

    protected override object GetInstance(Type service, string key)
    {
        return _container.GetInstance(service, key);
    }

    protected override IEnumerable<object> GetAllInstances(Type service)
    {
        return _container.GetAllInstances(service);
    }

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

+1

c # visual-studio wpf caliburn.micro

Qobus 05 june 17 at 15:18

source share

1 answer

mm8 · Accepted Answer · 2017-06-05T15:29:47+0000

Try to override the method Configure

and register your view's model type:

public class AppBootstrapper : BootstrapperBase
{
    private SimpleContainer _container = new SimpleContainer();

    public AppBootstrapper()
    {
        Initialize();
    }

    protected override void Configure()
    {
        _container.Singleton<IWindowManager, WindowManager>();
        _container.Singleton<IEventAggregator, EventAggregator>();
        _container.RegisterPerRequest(typeof(AppViewModel), null, typeof(AppViewModel));
    }

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

    protected override object GetInstance(Type service, string key)
    {
        return _container.GetInstance(service, key);
    }

    protected override IEnumerable<object> GetAllInstances(Type service)
    {
        return _container.GetAllInstances(service);
    }

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

NullReferenceException on DisplayRootViewFor <>

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