Sending Messages in CommunityToolkit

[Elencon]

Hello
Visual Studio 17.2.6
and "CommunityToolkit.Mvvm" Version="7.1.2"

1. I created WPF Application project
2. Fixed compilation problems with Source Generators with workaround:
   Fix build when using source generators (#6534) dotnet/wpf#6680 (comment)
   3)Here is MyViewModel code
   namespace CommunityToolkit;

public class TestMessage
{
}

public class MyViewModel : ObservableRecipient,
IRecipient
{
private string _first_name;
public string FirstName
{
get => _first_name;
set => SetProperty(ref _first_name, value);
}

private string _last_name;
public string LastName
{
    get => _last_name; 
    set => SetProperty(ref _last_name, value);
}

public MyViewModel()
{
    FirstName = "John";
    LastName = "Doe";
    SendMessage();
}

public void SendMessage()
{
    WeakReferenceMessenger.Default.Send(new TestMessage());
}
public void Receive(TestMessage m)
{
    int a = 0;
}

}

4. I see that SendMessage is executed in debugger, but Receive function is not called
   Here is my MainWindow.xaml

<Grid.ColumnDefinitions>


</Grid.ColumnDefinitions>
<Grid.RowDefinitions>




</Grid.RowDefinitions>

    <TextBlock Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2" Margin="4" Text="{Binding FullName}" HorizontalAlignment="Center" FontWeight="Bold"/>

    <Label Grid.Column="0" Grid.Row="1" Margin="4" Content="First Name:" HorizontalAlignment="Right"/>
    <!-- UpdateSourceTrigger=PropertyChanged makes sure that changes in the TextBoxes are immediately applied to the model. -->
    <TextBox Grid.Column="1" Grid.Row="1" Margin="4" Text="{Binding FirstName, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Width="200"/>

    <Label Grid.Column="0" Grid.Row="2" Margin="4" Content="Last Name:" HorizontalAlignment="Right"/>
    <TextBox Grid.Column="1" Grid.Row="2" Margin="4" Text="{Binding LastName, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left"  Width="200"/>

    <Label Grid.Column="0" Grid.Row="3" Margin="4" Content="Age:" HorizontalAlignment="Right"/>
    <TextBlock Grid.Column="1" Grid.Row="3" Margin="4" Text="{Binding Age}" HorizontalAlignment="Left"/>
</Grid>

and MaimWindow.xaml.cs
namespace CommunityToolkit;

///

/// Interaction logic for MainWindow.xaml
///

public partial class MainWindow : Window
{
private readonly MyViewModel _viewModel;

public MainWindow()
{
    InitializeComponent();
    _viewModel = new MyViewModel();
    // The DataContext serves as the starting point of Binding Paths
    DataContext = _viewModel;
}

}

What is wrong here ????

[CADTraveller]

You need to register the recipient, typically in the constructor; I don't see where you've done this. Have a look at the docs:

https://learn.microsoft.com/en-us/dotnet/communitytoolkit/mvvm/messenger