Prism error 'The region manager does not contain the region'

Question

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I am developing a Prism Sample application with WPF following MVVM pattern, but it has some problem in my application when it pass below code :

var view = _container.Resolve<DummyView>();
IRegion region = _regionMansger.Regions["ViewInjectionMain_MainRegion"];

I have tried out the solution proposed in other stackoverplow posts but it doesn't work.

( project github here ).

     class ViewInjectionMainViewModel : BindableBase
        {
            IUnityContainer _container;
            IRegionManager _regionMansger;
            public ViewInjectionMainViewModel(IUnityContainer container, IRegionManager regionManager)
            {
                _container = container;
                _regionMansger = regionManager;

                var view = _container.Resolve<DummyView>();
                IRegion region = _regionMansger.Regions["ViewInjectionMain_MainRegion"];

                region.Add(view);
            }
        }

  class Bootstrapper : UnityBootstrapper
    {
        protected override DependencyObject CreateShell()
        {               
            return this.Container.Resolve<MainWindow>();    
        }    

        protected override void InitializeShell()
        {
            base.InitializeShell();

            var regionManager = this.Container.Resolve<IRegionManager>();    

            if (regionManager != null)
            {
                regionManager.RegisterViewWithRegion("MainRegion", typeof(FirstView));
            }


            Container.RegisterType<object, RegionBasic>("RegionBasic");
            Container.RegisterType<object, RegionControlMain>("RegionControlMain");
            Container.RegisterType<object, DummyView>("DummyView");
            Container.RegisterType<object, ViewInjectionMain>("ViewInjectionMain");

            Application.Current.MainWindow.Show();
        }

        protected override void ConfigureModuleCatalog()
        {
            var catalog = (ModuleCatalog)ModuleCatalog;
            catalog.AddModule(typeof(ModuleA.ModuleAModule));
            catalog.AddModule(typeof(ModuleB.ModuleBModule));
            catalog.AddModule(typeof(DummyModule.DummyModuleClass));        
        }
    }

Thanks.

Answer 1

regionManager.RegisterViewWithRegion("MainRegion", typeof(FirstView));
                regionManager.RegisterViewWithRegion("ViewInjectionMain_MainRegion", typeof(DummyView)); //add this line

and get region via Dispatcher (the ViewInjectionMain.xaml should be loaded for loading ViewInjectionMain_MainRegion also)

class ViewInjectionMainViewModel :BindableBase
    {
        IUnityContainer _container;
        IRegionManager _regionMansger;
        public ViewInjectionMainViewModel(IUnityContainer container, IRegionManager regionManager)
        {
            _container = container;


            _regionMansger = regionManager;

            System.Windows.Application.Current.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Send, new Action(() =>
            {
                var view = _container.Resolve<DummyView>();


                IRegion region = _regionMansger.Regions["ViewInjectionMain_MainRegion"];


                region.Add(view);
            }));
        }

    }

Hope this will help you

Answer 2

I tested follow advice. I made some button and bound it to "DelegateCommand". It works. but when i made some function that "IRegion region = _regionMansger.Regions["ViewInjectionMain_MainRegion"];" and it call in constructor it doesn't work.

RegionManager contain region after view's viewmodel constructor ended.