[Shell,TitleView, Android] TitleView Bindings does not work with Android

[HobDev]

Description

The Text Property of Label.Text does not bind with ViewModel property in Android. Although it work if I do x:Reference with the page.

Steps to Reproduce

1. Create a TitleView and add a label within .
2. Bind Label.Text to a viewmodel property.
3. Deploy to app to iOS and Android.

Expected Behavior

the Text should display on iOS and Android

Actual Behavior

Text does not display on Android navigation bar.

Basic Information

• Version with issue:Xamarin.Forms-pre7
• Last known good version:
• IDE:Visual Studio for Mac preview
• Platform Target Frameworks:
  • iOS:
  • Android:
  • UWP:
• Android Support Library Version:
• Nuget Packages:
• Affected Devices:

###Don't Work

<Shell.TitleView>
       <Grid HorizontalOptions="FillAndExpand" VerticalOptions="Center" >
           <Label HorizontalOptions="Center" VerticalOptions="Center"  FontSize="22" Text="{Binding Title}"/>
       </Grid>
   </Shell.TitleView>

Work

<Shell.TitleView>
       <Grid HorizontalOptions="FillAndExpand" VerticalOptions="Center" >
           <Label HorizontalOptions="Center" VerticalOptions="Center"  FontSize="22" Text="{Binding Source={x:Reference thisPage}, Path=BindingContext.Title}"/>
       </Grid>
   </Shell.TitleView>

[HobDev]

It seems like Android have problem with any type of binding. Button commands also don't work with Android in Xamarin.Forms 4.

[gsemenov]

I have problem with binding in TitleView on ios (didn't test it on android) v.4.1.0.581479

[DaveNatalieTripArc]

I am seeing this issue again in the latest Maui dotnet 8 Preview 7 release.

Doesn't work on Android or Windows.

[PureWeen]

@DaveNatalieTripArc can you log an issue in the MAUI Repository?

I just tested locally against Preview7 and as far as I can tell the BC and Bindings are propagating fine.

[DaveNatalieTripArc]

Maybe I misunderstood this issue. I am trying to have my App Shell bind to the title specified in the Content Page.

Something like this.

<Shell
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
    <Shell.TitleView>
        <Label Text="{Binding Title}" />
    </Shell.TitleView>
</Shell>

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             Title="I WANT TO BIND THIS VALUE">
</ContentPage>

Is this possible?

[PureWeen]

Maybe I misunderstood this issue. I am trying to have my App Shell bind to the title specified in the Content Page.

Something like this.

<Shell
    x:Class="TripArc.ClientPortal.Mobile.AppShell"
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
    <Shell.TitleView>
        <Label Text="{Binding Title}" />
    </Shell.TitleView>
</Shell>

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             Title="I WANT TO BIND THIS VALUE">
</ContentPage>

Is this possible?

you'd need to set the bindingcontext of the page to the contentpage itself or use a bindingpath to the ContentPage https://learn.microsoft.com/en-us/dotnet/maui/fundamentals/data-binding/binding-path

[DaveNatalieTripArc]

That's what's not working in Preview 7. I don't know if it worked in previous versions.

Here's what I tried.

<Shell
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Name="myShell">
    <Shell.TitleView>
        <Label BindingContext="{x:Reference myShell}" Text="{Binding Path=CurrentPage.Title}" TextColor="Red" />
    </Shell.TitleView>

I apologize, I simplified my example above to show what I want to accomplish, and not my actual code that wasn't working.

[PureWeen]

That's what's not working in Preview 7. I don't know if it worked in previous versions.

Here's what I tried.

<Shell
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Name="myShell">
    <Shell.TitleView>
        <Label BindingContext="{x:Reference myShell}" Text="{Binding Path=CurrentPage.Title}" TextColor="Red" />
    </Shell.TitleView>

I apologize, I simplified my example above to show what I want to accomplish, and not my actual code that wasn't working.

CurrentPage isn't a bindable property

[DaveNatalieTripArc]

You said I should "use a bindingpath to the ContentPage"

What Path could I use that would get the me Title from the CurrentPage?