Back button missing on NavigationPage - xamarin.forms

Question

I'm using Prism.Forms 6.3 in a Xamarin.Forms 2.3.4.247 project. I'm having a hard time tracking why the back arrow button isn't visible when I navigate to a details page within a Master/Detail setup.
I can navigate to the Pages just fine, but the back-button never shows up. Instead, the hamburger menu icon is always visible. This is my "Master" page.
<?xml version="1.0" encoding="utf-8" ?>
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:FloatSink.Apps.Mobile.Views.ValueConverters"
xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="FloatSink.Apps.Mobile.Views.MainPage"
BackgroundColor="Blue">
<MasterDetailPage.Master>
<ContentPage Title="Menu">
<StackLayout Padding="40">
<Label Text="Hello" />
<Button Text="Feed" Command="{Binding NavigateCommand}" CommandParameter="NavigationPage/FeedPage" />
<Button Text="Options" Command="{Binding NavigateCommand}" CommandParameter="NavigationPage/OptionsPage" />
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>
</MasterDetailPage>
This is two of my Detail pages.
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="FloatSink.Apps.Mobile.Views.FeedPage">
<Label Text="Hello from Feed Page!" />
</ContentPage>
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="FloatSink.Apps.Mobile.Views.OptionsPage">
<Label Text="Hello from Options Page!" />
</ContentPage>
I navigate to it using the CommandParameter specified in my Master page, using the navigation service in the MainPageViewModel.
private void NavigateToPage(string uri)
{
this.navigationService.NavigateAsync(uri);
}
I've setup my NavigationPage like this during the startup of the app so I land on the FeedPage first, then I can navigate to the OptionsPage.
public class App : PrismApplication
{
public App(IPlatformInitializer dependencyRegister) : base(dependencyRegister) { }
protected override void OnInitialized()
{
base.NavigationService.NavigateAsync("MainPage/NavigationPage");
}
protected override void RegisterTypes()
{
var builder = new ContainerBuilder();
builder.RegisterModule<NavigationRegistration>();
builder.RegisterModule<ServicesRegistration>();
base.Container.RegisterTypeForNavigation<NavigationPage>();
// This is deprecated but we have to wait for Prism.Autofac to update itself
builder.Update(base.Container);
}
}
The DI registrations associated with navigation are done in this module:
internal class NavigationRegistration : Module
{
/// <summary>
/// Load the navigation related types into the given builder.
/// </summary>
/// <param name="builder">Container Builder that will be turned into the final IOC Container</param>
protected override void Load(ContainerBuilder builder)
{
// Register the NavigationPage in Xamarin with the Prism Navigation system.
//builder.RegisterType<NavigationPage>().AsSelf();
//PageNavigationRegistry.Register(nameof(NavigationPage), typeof(NavigationPage));
// Get all of the Types that represent a View in our assembly for DI and navigation registration
// If start-up time ever becomes an issue, we can replace this assembly scan with explicit registrations.
Type[] viewTypes = base.ThisAssembly.GetTypes().Where(type => type.IsAssignableTo<Page>()).ToArray();
// Iterate over each discovered View Type and register it with the navigation system and DI container.
for(int index = 0; index < viewTypes.Length; index++)
{
Type viewType = viewTypes[index];
builder.RegisterType(viewType).Named<Page>(viewType.Name);
// If we ever need to disconnect a view name from its Type name, we can do so here.
// We would build a custom attribute to decorate the view with, pull the attribute from the Type
// and register the Type with the attribute value.
PageNavigationRegistry.Register(viewType.Name, viewType);
}
}
}
Again I can each one of my detail pages without problem, the hamburger menu exists and I can open the Master page to view my buttons used for navigating. I just can't navigate backwards once I'm there. Is that something I'm supposed to wire up myself?

Answer 1

I'm not sure I'm reading your question right but it sounds like this is normal behavior. In my (short) experience with XF/Prism, every navigation from the master is a beginning of the stack. If you were to add another page, e.g. from Master->PageA->PageB, I would expect Page A to have the hamburger menu but going to PageB would give you the back arrow.

Answer 2

For using NavigationPage inside uri you should register it for navigation in the App.xaml.cs:
protected override void RegisterTypes()
{
// your registrations
Container.RegisterTypeForNavigation<NavigationPage>();
}
I most cases it is the reason.

Answer 3

To Navigate To Master Page
"/MasterPage/NavigationPage/ViewA"
To Navigate out of Master Page from ViewA and with back button
"ViewB"

Answer 4

You need to start your app with MainPage = new NavigationPage(new StartPage()); That is how it is solved in normal situation. So maybe try to register your MainPage wrapped in a NavigationPage.