MvvmCross 5.4 Android-Fragmente: Navigieren zu ViewModel nicht möglich

Question

Ich versuche, vom MainViewModel zum AccountsViewModel zu navigieren. Wenn die App startet, bleibt sie im MainViewModel hängen. Ich habe einiges an Debugging gemacht und bin mehrere Beispiele durchgegangen, aber ich kann dieses Problem nicht lösen. Die relevanten Klassen sind unten bitte lassen Sie mich wissen, wenn Sie noch etwas brauchen.

App

using DebtBuddy.Core.ViewModels; 
using MvvmCross.Core.ViewModels; 
using MvvmCross.Platform.IoC; 

namespace DebtBuddy.Core 
{ 
    public class App : MvxApplication 
    { 
     public override void Initialize() 
     { 
      CreatableTypes() 
       .EndingWith("Service") 
       .AsInterfaces() 
       .RegisterAsLazySingleton(); 

      CreatableTypes() 
       .EndingWith("Repository") 
       .AsInterfaces() 
       .RegisterAsLazySingleton(); 

      RegisterNavigationServiceAppStart<MainViewModel>(); 
     } 
    } 
} 

Einrichtung

using Android.Content; 
using MvvmCross.Core.ViewModels; 
using MvvmCross.Platform.Platform; 
using MvvmCross.Droid.Views; 
using MvvmCross.Droid.Support.V7.AppCompat; 
using DebtBuddy.Core.Repositories; 
using MvvmCross.Platform; 

namespace DebtBuddy.Droid 
{ 
    public class Setup : MvxAppCompatSetup 
    { 
     public Setup(Context applicationContext) : base(applicationContext) 
     { 
     } 

     protected override IMvxApplication CreateApp() 
     { 
      var dbConn = FileAccessHelper.GetLocalFilePath("account.db3"); 
      Mvx.RegisterSingleton(new AccountRepository(dbConn)); 

      return new Core.App(); 
     } 

     protected override IMvxTrace CreateDebugTrace() 
     { 
      return new DebugTrace(); 
     } 
    } 
} 

MainViewModel

using MvvmCross.Core.Navigation; 
using MvvmCross.Core.ViewModels; 

namespace DebtBuddy.Core.ViewModels 
{ 
    public class MainViewModel : MvxViewModel 
    { 
     private readonly IMvxNavigationService _navigationService; 

     public MainViewModel(IMvxNavigationService navigationService) 
     { 
      _navigationService = navigationService; 

      ShowAccountsViewModel = new MvxAsyncCommand(async() => await 
      _navigationService.Navigate<AccountsViewModel>()); 
     } 

     public IMvxAsyncCommand ShowAccountsViewModel { get; private set; } 
    } 
} 

Mainview

using Android.App; 
using MvvmCross.Droid.Support.V7.AppCompat; 
using DebtBuddy.Core.ViewModels; 
using Android.OS; 
using MvvmCross.Droid.Views.Attributes; 

namespace DebtBuddy.Droid.Views 
{ 
    [MvxActivityPresentation] 
    [Activity(Theme = "@style/AppTheme")] 
    public class MainView : MvxAppCompatActivity<MainViewModel> 
    { 
     protected override void OnCreate(Bundle bundle) 
     { 
      base.OnCreate(bundle); 

      SetContentView(Resource.Layout.MainView); 

      ViewModel.ShowAccountsViewModel.ExecuteAsync(); 
     } 
    } 
} 

MainView.axml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:local="http://schemas.android.com/apk/res-auto" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
    <FrameLayout 
     android:id="@+id/content_frame" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" /> 
</LinearLayout> 

AccountsViewModel

using System.Collections.ObjectModel; 
using DebtBuddy.Core.Extensions; 
using DebtBuddy.Core.Interfaces.IDataServices; 
using DebtBuddy.Core.Models; 
using MvvmCross.Core.Navigation; 
using MvvmCross.Core.ViewModels; 

namespace DebtBuddy.Core.ViewModels 
{ 
    public class AccountsViewModel : MvxViewModel 
    { 
     private readonly IAccountDataService _accountDataService; 
     private readonly IMvxNavigationService _navigationService; 

     public AccountsViewModel(IMvxNavigationService navigationService, IAccountDataService accountDataService) 
     { 
      _navigationService = navigationService; 
      _accountDataService = accountDataService; 

      ShowCreateAccountViewModelCommand = new MvxAsyncCommand(async() => await _navigationService.Navigate<CreateAccountViewModel>()); 
      ShowAccountDetailViewModelCommand = new MvxAsyncCommand<Account (item => _navigationService.Navigate<AccountDetailViewModel, Account>(item)); 
     } 

     public IMvxAsyncCommand ShowCreateAccountViewModelCommand { get; private set; } 

     public IMvxAsyncCommand<Account> ShowAccountDetailViewModelCommand { get; private set; } 

     private ObservableCollection<Account> _accounts; 
     public ObservableCollection<Account> Accounts 
     { 
      get => _accounts; 
      set 
      { 
       _accounts = value; 
       RaisePropertyChanged(() => Accounts); 
      } 
     } 

     public override void Prepare() 
     { 
      LoadAccountsFromDatabase(); 
     } 

     private async void LoadAccountsFromDatabase() 
     { 
      Accounts = (await _accountDataService.GetAllAccounts()).ToObservableCollection(); 
     } 
    } 
} 

AccountsView

using Android.OS; 
using MvvmCross.Droid.Views.Attributes; 
using DebtBuddy.Core.ViewModels; 
using MvvmCross.Droid.Support.V4; 
using Android.Runtime; 
using Android.Views; 
using MvvmCross.Binding.Droid.BindingContext; 

namespace DebtBuddy.Droid.Views 
{ 
    [MvxFragmentPresentation(typeof(MainViewModel), Resource.Id.content_frame, true)] 
    [Register(nameof(AccountsView))] 
    public class AccountsView : MvxFragment<AccountsViewModel> 
    { 
     public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
     { 
      base.OnCreateView(inflater, container, savedInstanceState); 

      var view = this.BindingInflate(Resource.Layout.AccountsView, null); 

      return view; 
     } 
    } 
} 

AccountsView.axml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:local="http://schemas.android.com/apk/res-auto" 
    android:id="@+id/main_frame" 
    android:orientation="vertical" 
    android:background="@color/white" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
    <Mvx.MvxListView 
     android:id="@+id/account_list" 
     android:divider="@null" 
     android:scrollbars="vertical" 
     android:choiceMode="singleChoice" 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:layout_weight="1" 
     android:layout_gravity="left|start" 
     local:MvxItemTemplate="@layout/item_account" 
     local:MvxBind="ItemsSource Accounts; ItemClick ShowAccountDetailViewModelCommand" /> 
    <Button 
     android:id="@+id/addAccountButton" 
     android:background="@color/white" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_weight="0" 
     android:text="Add Account" 
     android:textSize="17dp" 
     android:textColor="@color/black" 
     local:MvxBind="Click ShowCreateAccountViewModelCommand" /> 
</LinearLayout> 

Answer 1

Haben Sie Ihre Setup-Klasse, die als eine von MvvmCross Probe here

Der entscheidende Punkt ist, MvxAppCompatViewPresenter zu verwenden.