MVVM: Good way to close dialog and set DialogResult

最新推荐文章于 2023-10-01 11:08:11 发布

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#DialogResult #MVVM #wpf #WPF

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本文介绍了一种在MVVM模式下简化对话框操作的方法，通过使用自定义的附加属性`DialogCloser`，使得ViewModel可以直接控制对话框的关闭及返回值，无需额外的代码隐藏文件。

I was inspired by Thejuan's answer to write a simpler attached property. No styles, no triggers; instead, you can just do this:

<Window ...
        xmlns:xc="clr-namespace:ExCastle.Wpf"
        xc:DialogCloser.DialogResult="{Binding DialogResultValue}">

This is almost as clean as if the WPF team had gotten it right and made DialogResult a dependency property in the first place. Just put abool? DialogResult property on your ViewModel and implement INotifyPropertyChanged, and voilà, your ViewModel can close the Window (and set its DialogResult) just by setting a property. MVVM as it should be.

Here's the code for DialogCloser:

using System.Windows;

namespace ExCastle.Wpf
{
    public static class DialogCloser
    {
        public static readonly DependencyProperty DialogResultProperty =
            DependencyProperty.RegisterAttached(
                "DialogResult",
                typeof(bool?),
                typeof(DialogCloser),
                new PropertyMetadata(DialogResultChanged));

        private static void DialogResultChanged(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            var window = d as Window;
            if (window != null)
                window.DialogResult = e.NewValue as bool?;
        }
        public static void SetDialogResult(Window target, bool? value)
        {
            target.SetValue(DialogResultProperty, value);
        }
    }
}

From: http://blog.excastle.com/2010/07/25/mvvm-and-dialogresult-with-no-code-behind/

More changes by me as below:

You can add property DialogResultValue to your ViewModelBase if you have more view model for dialogs. You also can add it directly to your view model not to base.

public abstract class DialogVMBase : VMBase
{
    public DialogVMBase()
      : base()
    {
    }

    private bool? _dialogResult;
    public bool? DialogResultValue
    {
      get { return _dialogResult; }
      set
      {
        if (_dialogResult != value)
        {
          _dialogResult = value;
          this.RaisePropertyChanged(() => DialogResultValue);
        }
      }
    }
}

Below is example to use it.

In your ViewModel.cs

public class MyViewModel : DialogViewModelBase
{

public RelayCommand OkCommand { get; set; }

    public MyViewModel()
      : base()
    {
      OkCommand = new RelayCommand(Ok_Executed);
    }

    private void Ok_Executed()
    {
      DialogResultValue = true;
    }

}

In your MyWindow.xaml:

In window to use MyWindow:

    private void ShowMyWindow_Executed()
    {
        MyWindow dlg = new MyWindow();

if(dlg.ShowDialog()==true)

{