Mahapps 1.3 对话框和 Avalon.Wizard

Question

我集成了流行的 UI 库 Mahapps with the Avalon.Wizard 控件。

它集成得很好，但我对 Mahapps 对话框有疑问。向导控件定义了一个 InitializeCommand 来处理向导页面上的输入。

显然，InitializeCommand 在附加到视图的依赖项属性初始化 (DialogParticipation.Register) 之前被触发。

这会导致以下错误：

Context is not registered. Consider using DialogParticipation.Register in XAML to bind in the DataContext.

重现该问题的示例项目可用here。

关于如何解决这个问题有什么建议吗？

Answer 1

页面 Xaml 不是在初始化命令中创建的，所以此时您不能使用 DialogCoordinator。

这是一个带有 LoadedCommand 的自定义接口，您可以在 ViewModel 中实现它并在后面的 Xaml 代码中调用它。

public interface IWizardPageLoadableViewModel
{
    ICommand LoadedCommand { get; set; }
}

视图模型：

public class LastPageViewModel : WizardPageViewModelBase, IWizardPageLoadableViewModel
{
    public LastPageViewModel()
    {
        Header = "Last Page";
        Subtitle = "This is a test project for Mahapps and Avalon.Wizard";

        InitializeCommand = new RelayCommand<object>(ExecuteInitialize);
        LoadedCommand = new RelayCommand<object>(ExecuteLoaded);
    }

    public ICommand LoadedCommand { get; set; }

    private async void ExecuteInitialize(object parameter)
    {
        // The Xaml is not created here! so you can't use the DialogCoordinator here.
    }

    private async void ExecuteLoaded(object parameter)
    {
        var dialog = DialogCoordinator.Instance;
        var settings = new MetroDialogSettings()
        {
            ColorScheme = MetroDialogColorScheme.Accented
        };
        await dialog.ShowMessageAsync(this, "Hello World", "This dialog is triggered from Avalon.Wizard LoadedCommand", MessageDialogStyle.Affirmative, settings);
    }
}

和视图：

public partial class LastPageView : UserControl
{
    public LastPageView()
    {
        InitializeComponent();
        this.Loaded += (sender, args) =>
        {
            DialogParticipation.SetRegister(this, this.DataContext);
            ((IWizardPageLoadableViewModel) this.DataContext).LoadedCommand.Execute(this);
        };
        // if using DialogParticipation on Windows which open / close frequently you will get a
        // memory leak unless you unregister.  The easiest way to do this is in your Closing/ Unloaded
        // event, as so:
        //
        // DialogParticipation.SetRegister(this, null);
        this.Unloaded += (sender, args) => { DialogParticipation.SetRegister(this, null); };
    }
}

希望对您有所帮助。

Mahapps 1.3 对话框和 Avalon.Wizard

Mahapps 1.3 dialogs and Avalon.Wizard

c#

wpf

mahapps.metro