[C#] MVVM을 사용하는 wpf의 대화 상자에 대한 좋은 습관 또는 나쁜 습관?

최근에 wpf 앱에 대한 추가 및 편집 대화 상자를 만드는 데 문제가있었습니다.

내 코드에서하고 싶은 것은 이것과 같습니다. (주로 mvvm과 함께 viewmodel 첫 번째 접근 방식을 사용합니다)

대화창을 호출하는 ViewModel :

var result = this.uiDialogService.ShowDialog("Dialogwindow Title", dialogwindowVM);
// Do anything with the dialog result

어떻게 작동합니까?

먼저 대화 서비스를 만들었습니다.

public interface IUIWindowDialogService
{
    bool? ShowDialog(string title, object datacontext);
}

public class WpfUIWindowDialogService : IUIWindowDialogService
{
    public bool? ShowDialog(string title, object datacontext)
    {
        var win = new WindowDialog();
        win.Title = title;
        win.DataContext = datacontext;

        return win.ShowDialog();
    }
}

WindowDialog특별하지만 간단한 창입니다. 내 콘텐츠를 보유하려면 필요합니다.

<Window x:Class="WindowDialog"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    Title="WindowDialog"
    WindowStyle="SingleBorderWindow"
    WindowStartupLocation="CenterOwner" SizeToContent="WidthAndHeight">
    <ContentPresenter x:Name="DialogPresenter" Content="{Binding .}">

    </ContentPresenter>
</Window>

wpf의 대화 상자 문제 dialogresult = true는 코드에서만 가능하다는 것입니다. 그렇기 때문에 dialogviewmodel구현할 인터페이스를 만들었 습니다.

public class RequestCloseDialogEventArgs : EventArgs
{
    public bool DialogResult { get; set; }
    public RequestCloseDialogEventArgs(bool dialogresult)
    {
        this.DialogResult = dialogresult;
    }
}

public interface IDialogResultVMHelper
{
    event EventHandler<RequestCloseDialogEventArgs> RequestCloseDialog;
}

내 ViewModel이 시간이라고 생각할 때마다이 dialogresult = true이벤트를 발생시킵니다.

public partial class DialogWindow : Window
{
    // Note: If the window is closed, it has no DialogResult
    private bool _isClosed = false;

    public DialogWindow()
    {
        InitializeComponent();
        this.DialogPresenter.DataContextChanged += DialogPresenterDataContextChanged;
        this.Closed += DialogWindowClosed;
    }

    void DialogWindowClosed(object sender, EventArgs e)
    {
        this._isClosed = true;
    }

    private void DialogPresenterDataContextChanged(object sender,
                              DependencyPropertyChangedEventArgs e)
    {
        var d = e.NewValue as IDialogResultVMHelper;

        if (d == null)
            return;

        d.RequestCloseDialog += new EventHandler<RequestCloseDialogEventArgs>
                                    (DialogResultTrueEvent).MakeWeak(
                                        eh => d.RequestCloseDialog -= eh;);
    }

    private void DialogResultTrueEvent(object sender,
                              RequestCloseDialogEventArgs eventargs)
    {
        // Important: Do not set DialogResult for a closed window
        // GC clears windows anyways and with MakeWeak it
        // closes out with IDialogResultVMHelper
        if(_isClosed) return;

        this.DialogResult = eventargs.DialogResult;
    }
 }

이제 적어도 DataTemplate내 리소스 파일 ( app.xaml또는 무언가) 을 만들어야합니다 .

<DataTemplate DataType="{x:Type DialogViewModel:EditOrNewAuswahlItemVM}" >
        <DialogView:EditOrNewAuswahlItem/>
</DataTemplate>

자, 이제 뷰 모델에서 대화 상자를 호출 할 수 있습니다.

 var result = this.uiDialogService.ShowDialog("Dialogwindow Title", dialogwindowVM);

이제 내 질문에,이 솔루션에 문제가 있습니까?

편집 : 완전성을 위해. ViewModel은 구현해야 IDialogResultVMHelper하며 다음과 같이 만들 수 있습니다 OkCommand.

public class MyViewmodel : IDialogResultVMHelper
{
    private readonly Lazy<DelegateCommand> _okCommand;

    public MyViewmodel()
    {
         this._okCommand = new Lazy<DelegateCommand>(() =>
             new DelegateCommand(() =>
                 InvokeRequestCloseDialog(
                     new RequestCloseDialogEventArgs(true)), () =>
                         YourConditionsGoesHere = true));
    }

    public ICommand OkCommand
    {
        get { return this._okCommand.Value; }
    }

    public event EventHandler<RequestCloseDialogEventArgs> RequestCloseDialog;
    private void InvokeRequestCloseDialog(RequestCloseDialogEventArgs e)
    {
        var handler = RequestCloseDialog;
        if (handler != null)
            handler(this, e);
    }
 }

편집 2 : 내 이벤트 핸들러가 약한 등록하기 위해 여기에서 코드를 사용 :
http://diditwith.net/2007/03/23/SolvingTheProblemWithEventsWeakEventHandlers.aspx
(웹 사이트가 더 이상 존재하지 않는, WebArchive 미러 )

public delegate void UnregisterCallback<TE>(EventHandler<TE> eventHandler)
    where TE : EventArgs;

public interface IWeakEventHandler<TE>
    where TE : EventArgs
{
    EventHandler<TE> Handler { get; }
}

public class WeakEventHandler<T, TE> : IWeakEventHandler<TE>
    where T : class
    where TE : EventArgs
{
    private delegate void OpenEventHandler(T @this, object sender, TE e);

    private readonly WeakReference mTargetRef;
    private readonly OpenEventHandler mOpenHandler;
    private readonly EventHandler<TE> mHandler;
    private UnregisterCallback<TE> mUnregister;

    public WeakEventHandler(EventHandler<TE> eventHandler,
                                UnregisterCallback<TE> unregister)
    {
        mTargetRef = new WeakReference(eventHandler.Target);

        mOpenHandler = (OpenEventHandler)Delegate.CreateDelegate(
                           typeof(OpenEventHandler),null, eventHandler.Method);

        mHandler = Invoke;
        mUnregister = unregister;
    }

    public void Invoke(object sender, TE e)
    {
        T target = (T)mTargetRef.Target;

        if (target != null)
            mOpenHandler.Invoke(target, sender, e);
        else if (mUnregister != null)
        {
            mUnregister(mHandler);
            mUnregister = null;
        }
    }

    public EventHandler<TE> Handler
    {
        get { return mHandler; }
    }

    public static implicit operator EventHandler<TE>(WeakEventHandler<T, TE> weh)
    {
        return weh.mHandler;
    }
}

public static class EventHandlerUtils
{
    public static EventHandler<TE> MakeWeak<TE>(this EventHandler<TE> eventHandler,
                                                    UnregisterCallback<TE> unregister)
        where TE : EventArgs
    {
        if (eventHandler == null)
            throw new ArgumentNullException("eventHandler");

        if (eventHandler.Method.IsStatic || eventHandler.Target == null)
            throw new ArgumentException("Only instance methods are supported.",
                                            "eventHandler");

        var wehType = typeof(WeakEventHandler<,>).MakeGenericType(
                          eventHandler.Method.DeclaringType, typeof(TE));

        var wehConstructor = wehType.GetConstructor(new Type[]
                             {
                                 typeof(EventHandler<TE>), typeof(UnregisterCallback<TE>)
                             });

        IWeakEventHandler<TE> weh = (IWeakEventHandler<TE>)wehConstructor.Invoke(
                                        new object[] { eventHandler, unregister });

        return weh.Handler;
    }
}

답변

event EventHandler<RequestCloseEventArgs> RequestCloseDialog;

public class RequestCloseEventArgs : EventArgs
{
    public RequestCloseEventArgs(bool dialogResult)
    {
        this.DialogResult = dialogResult;
    }

    public bool DialogResult { get; private set; }
}