IDialogAware

The IDialogAware interface has undergone some updates in Prism 9 to help you write code that better meets your needs by providing a more robust API that is able to adapt to your needs.

public interface IDialogAware
{
    bool CanCloseDialog();
    void OnDialogClosed();
    void OnDialogOpened(IDialogParameters parameters)
    DialogCloseListener RequestClose { get; }
}

Can Close

The IDialogAware interface provides the method CanCloseDialog(). This allows you to provide any custom logic that you may require to determine whether or not the Dialog should be allowed to close:

public class MyDialogViewModel : IDialogAware
{
    private string? _name;
    public string? Name
    {
        get => _name;
        set => SetProperty(ref _name, value)
    }

    public bool CanCloseDialog() => !string.IsNullOrEmpty(Name);
}

DialogCloseListener

The DialogCloseListener is new in Prism 9 and replaces the event that was in the original API. The DialogCloseListener allows you more flexibility and is part of the Dialog Service's enhanced API.

Note

The RequestClose property should be implemented as shown below. This property is set by DialogService itself and should not be set by your code.

public class MyDialogViewModel : IDialogAware
{
    public DialogCloseListener RequestClose { get; }
}

Using the DialogCloseListener

One of the benefits of the DialogCloseListener is that it allows you more flexibility when invoking it.

private void OnMyCommandExecuted()
{
    // Option 1.
    RequestClose.Invoke();

    // Option 2.
    RequestClose.Invoke(new DialogParameters{ { "MyParameter", SomeValue } });

    // Option 3.
    RequestClose.Invoke(ButtonResult.OK);

    // Option 4.
    RequestClose.Invoke(new DialogParameters{ { "MyParameter", SomeValue } }, ButtonResult.OK);

    // Option 5.
    var result = new DialogResult
    {
        Parameters = new DialogParameters{ { "MyParameter", SomeValue } },
        Result = ButtonResult.OK
    };
    RequestClose.Invoke(result);
}

Additional Considerations

When building apps with .NET MAUI you may want to consider using Popup Pages. With the Commercial Plus license you can take advantage of the Prism.Plugin.Popups package for .NET MAUI.