Prism.NavigationEx

Prism.NavigationEx provides ViewModel first navigation for Prism.Forms.

Setup

Install NuGet package.

Prism.NavigationEx

Usage

You can specify targert ViewModel and parameter type for navigation.

public class MainPageViewModel : NavigationViewModel
{
    public DelegateCommand GoToNextCommand { get; }

    public MainPageViewModel(INavigationService navigationService) : base(navigationService)
    {
        GoToNextCommand = new DelegateCommand(() => NavigateAsync<NextPageViewModel, int>(100));
    }
}

public class NextPageViewModel : NavigationViewModel<int>
{
    private int _parameter;
    
    public DelegateCommand GoBackCommand { get; }

    public NextPageViewModel(INavigationService navigationService) : base(navigationService)
    {
        GoBackCommand = new DelegateCommand(() => GoBackAsync());
    }

    public override void Prepare(int parameter)
    {
        _parameter = parameter;
    }
}

If you want to return result, you can do as follows.

public class MainPageViewModel : NavigationViewModel
{
    public DelegateCommand GoToNextCommand { get; }

    public MainPageViewModel(INavigationService navigationService) : base(navigationService)
    {
        GoToNextCommand = new DelegateCommand(async () =>
        {
            var result = await NavigateAsync<NextPageViewModel, int, string>(100);
            if (result.Success)
            {
                var data = result.Data;
                ...
            }
        });
    }
}

public class NextPageViewModel : NavigationViewModel<int, string>
{
    private int _parameter;
    
    public DelegateCommand GoBackCommand { get; }

    public NextPageViewModel(INavigationService navigationService) : base(navigationService)
    {
        GoBackCommand = new DelegateCommand(() => GoBackAsync("result"));
    }

    public override void Prepare(int parameter)
    {
        _parameter = parameter;
    }
}

If you don't need initializing, you can use NavigationViewModelResult.

Wrap in NavigationPage

If wrapInNavigationPage argument is true, thie next page is wrapped in NavigationPage.

NavigateAsync<NextPageViewModel>(wrapInNavigationPage: true);

Clear navigation stack

If noHistory argument is true, navigation stack is cleared.

NavigateAsync<NextPageViewModel>(noHistory: true);

Confirm navigation

You can provide a canNavigate argument which determines whether or not navigation can be done.

NavigateAsync<NextPageViewModel>(canNavigate: () => pageDialogService.DisplayAlertAsync("title", "message", "OK", "Cancel");

Replace current page

If replaced argument is true, current page is replaced.

NavigateAsync<NextPageViewModel>(replaced: true);

Deep Link

This library supports deep link.

var navigation = NavigationFactory.Create<MainPageViewModel>()
                                  .Add<NextPageViewModel, int>(100);
                                  .Add<NextNextPageViewModel, int>(200);

NavigateAsync(navigation, wrapInNavigationPage: true);

If you want to return result in the middle of link, you can do as follows.

var navigation = NavigationFactory.Create<MainPageViewModel, string>((viewModel, result) => 
                                  {
                                      if (result.Success && viewModel is MainPageViewModel mainPageViewModel)
                                      {
                                          var data = result.Data;
                                          ...
                                      }
                                  })
                                  .Add<NextPageViewModel, int, string>(100, (viewModel, result) => 
                                  {
                                      if (result.Success && viewModel is NextPageViewModel nextPageViewModel)
                                      {
                                          var data = result.Data;
                                          ...
                                      }
                                  })
                                  .Add<NextNextPageViewModel, int>(200);

NavigateAsync(navigation, wrapInNavigationPage: true);

TabbedPage

You can create tab by specifying ViewModel and parameter type. If wrapInNavigationPage is true, the tab is wrapped in NavigationPage.

var navigation = NavigationFactory.Create<MyTabbedPageViewModel>(null, new Tab<FirstTabPageViewModel, string>("text", true), new Tab<SecondTabPageViewModel>());

NavigateAsync(navigation, noHistory: true);

You can use NavigateTabbedPageAsync if you want to navigate to default TabbedPage.

NavigateTabbedPageAsync(null, true, false, true, false, 
                        new Tab<FirstTabPageViewModel, string>("text", true), 
                        new Tab<SecondTabPageViewModel>());

Registering all pages

This library provides the way of registering your all pages, NavigationPage and TabbedPage.

protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
    containerRegistry.RegisterForNavigation(this);
}

NavigationNameProvider

By default, a target page name for a ViewModel is the ViewModel name which "ViewModel"　is removed from. If you want to use other pages, you can customize it.

NavigationNameProvider.SetDefaultViewModelTypeToNavigationNameResolver(viewModelType =>
{
    ...
});

If you want to use other NavigationPage, you can change it.

NavigationNameProvider.DefaultNavigationPageName = nameof(MyNavigationPage);

If you want to use other TabbedPage for NavigateTabbedPageAsync, you can change it.

NavigationNameProvider.DefaultTabbedPageName = nameof(MyTabbedPage);