Invoke a WPF PRISM dialog window of different module

Question

I have a WPF PRISM application with regions -- Menu Region and workspace Region. When the menu is clicked appropriate view/form is opened inside workspace region. I have different modules like Employee, Organization, Finance, etc... with each module having multiple views/forms.

I have a requirement to open a view/form from Finance module as a dialog window when a button in the employee view/form (Module - Employee) is clicked.

Is there a way to achieve the same in PRISM?

[Edit 1]: The 2 modules are independent modules. I do not wish to add a reference of Finance module to Employee module. As further down I may have a requirement to show Employee as a dialog window from one or many Finance views.

Big AL Big AL · Accepted Answer · 2015-12-20T10:21:20

Sure - here are two ways for you to consider.

Option 1

Prism's documentation has a section on "Making a command globally available" using their CompositeCommand class. To do this, create a public static class in a common library that both assemblies can reference:

public static class GlobalCommands
{
    public static CompositeCommand ShowFinanceFormCommand = new CompositeCommand();
}

In the Finance form viewmodel, you would register your actual command (which has all the logic for showing the form) with:

public FinanceViewModel()
{
    GlobalCommands.ShowFinanceFormCommand.RegisterCommand(this.ShowFinancePopupCommand); 
}

In the employee view model, bind your button's ICommand to the ShowFinanceFormCommand composite command.

public EmployeeViewModel()
{
    this.EmployeeShowFinanceFormCommand = GlobalCommands.ShowFinanceFormCommand;
}

Option 2

If you need to broadcast events across modules in a loosely coupled fashion, use Prism's EventAggregator class. To implement this, create a ShowFinanceFormEvent in a common assembly that both can reference. In the employee viewmodel, publish an event when the button is pressed. In the finance viewmodel, subscribe to that event and react accordingly.

// This sits in a separate module that both can reference
public class ShowFinanceFormEvent : PubSubEvent<object>
{
}

public class EmployeeViewModel
{
    private readonly IEventAggregator eventAggregator;

    public EmployeeViewModel(IEventAggregator eventAggregator)
    {
        this.ShowFormCommand = new DelegateCommand(RaiseShowFormEvent);
        this.eventAggregator = eventAggregator;
    }

    public ICommand ShowFormCommand { get; }

    private void RaiseShowFormEvent()
    {
        // Notify any listeners that the button has been pressed
        this.eventAggregator.GetEvent<ShowFinanceFormEvent>().Publish(null);
    }
}

public class FinanceViewModel
{
    public FinanceViewModel(IEventAggregator eventAggregator)
    {
        // subscribe to button click events
        eventAggregator.GetEvent<ShowFinanceFormEvent>().Subscribe(this.ShowForm);

        this.ShowFinanceFormRequest = new InteractionRequest<INotification>();
    }

    public InteractionRequest<INotification> ShowFinanceFormRequest { get; }

    private void ShowForm(object src)
    {
        // Logic goes here to show the form... e.g.
        this.ShowFinanceFormRequest.Raise(
            new Notification { Content = "Wow it worked", Title = "Finance form title" });
    }
}

Invoke a WPF PRISM dialog window of different module

2 Answers