Prism WPF Binding RegionManager.RegionName

Question

I have a Prism 7 application with two modules, called ModuleA and ModuleB. In my main window I would like to be able to show either ModuleA if "Show A" button is clicked or ModuleB if "Show B" button is clicked. I implemented the behaviour the following way:

MainWindow.xaml

<Window x:Class="ModulesTest.Views.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:prism="http://prismlibrary.com/"
    prism:ViewModelLocator.AutoWireViewModel="True"
    Title="{Binding Title}" Height="350" Width="525">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <ContentControl prism:RegionManager.RegionName="{Binding Module}" />
    <StackPanel Grid.Row="1">
        <Button Command="{Binding ShowModuleCommand}"
                CommandParameter="A">
            Show A
        </Button>
        <Button Command="{Binding ShowModuleCommand}"
                CommandParameter="B">
            Show B
        </Button>
    </StackPanel>
    
</Grid>

MainWindowViewModel.cs

public class MainWindowViewModel : BindableBase
{
    private string _title = "Prism Application";
    public string Title
    {
        get { return _title; }
        set { SetProperty(ref _title, value); }
    }

    private string fieldName;
    public string Module
    {
        get { return fieldName; }
        set { SetProperty(ref fieldName, value); }
    }

    private DelegateCommand<string> _showModuleCommand;
    public DelegateCommand<string> ShowModuleCommand =>
        _showModuleCommand ?? (_showModuleCommand = new DelegateCommand<string>(ExecuteShowModuleCommand));

    void ExecuteShowModuleCommand(string module)
    {
        Module = "Module" + module;
    }

    public MainWindowViewModel()
    {
        Module = "ModuleA";
    }
}

The problem is that the RegionManager.RegionName remains "ModuleA" as set in the constructor of the ViewModel and doesn't change when "Show B" is clicked. Is the binding of the RegionManager.RegionName not allowed by design or am I doing it wrong?

Here's also the link to the repo: https://github.com/moisejbraver/ModulesTest

Answer 1

A region is a structural part of your user interface. You should not reassign the region name once it has been assigned to a specific control.

If you need to navigate inside a region, consider using the IRegionNavigationService...