一个有趣的替代方法是使用控制器来显示视图(对话框)。

WPF应用程序框架(WAF)说明了这是如何工作的。

编辑:10多年后，我可以看出使用Mediator或任何其他消息传递模式在很多层面上都是一个非常糟糕的主意。不要这样做，只需实现Jeffrey的答案或在视图模型中注入一个IDialogService即可。

你应该找个中间人。 Mediator是一种常见的设计模式，在某些实现中也称为Messenger。 它是一种Register/Notify类型的范例，允许ViewModel和Views通过低耦合消息传递机制进行通信。

你应该看看谷歌WPF门徒组，然后搜索调解员。 你会很高兴得到答案的……

但是你可以这样开始:

http://joshsmithonwpf.wordpress.com/2009/04/06/a-mediator-prototype-for-wpf-apps/

享受吧!

编辑:你可以看到这个问题的答案与MVVM轻工具包在这里:

http://mvvmlight.codeplex.com/Thread/View.aspx?ThreadId=209338

在询问任务或对话框的视图模型应该是什么样子时，我也在思考一个类似的问题。

我目前的解决方案是这样的:

public class SelectionTaskModel<TChoosable> : ViewModel
    where TChoosable : ViewModel
{
    public SelectionTaskModel(ICollection<TChoosable> choices);
    public ReadOnlyCollection<TChoosable> Choices { get; }
    public void Choose(TChoosable choosen);
    public void Abort();
}

当视图模型决定需要用户输入时，它会调出一个SelectionTaskModel实例，其中包含用户可能的选择。基础设施负责调出相应的视图，该视图在适当的时候根据用户的选择调用Choose()函数。

Sorry, but I have to chime in. I have been through several of the suggested solutions, before finding the Prism.Wpf.Interactivity namespace in the Prism project. You can use interaction requests and popup window action to either roll a custom window or for simpler needs there are built in Notification and Confirmation popups. These create true windows and are managed as such. you can pass a context object with any dependencies you need in the dialog. We use this solution at my work since I found it. We have numerous senior devs here and noone has come up with anything better. Our previous solution was the dialog service into an overlay and using a presenter class to make it happen, but you had to have factories for all of the dialog viewmodels, etc.

这不是小事，但也不是超级复杂。而且它是内置在Prism中，因此是最好(或更好)的实践。

我的2分钱!

使用可冻结命令

<Grid>
        <Grid.DataContext>
            <WpfApplication1:ViewModel />
        </Grid.DataContext>


        <Button Content="Text">
            <Button.Command>
                <WpfApplication1:MessageBoxCommand YesCommand="{Binding MyViewModelCommand}" />
            </Button.Command>
        </Button>

</Grid>

public class MessageBoxCommand : Freezable, ICommand
{
    public static readonly DependencyProperty YesCommandProperty = DependencyProperty.Register(
        "YesCommand",
        typeof (ICommand),
        typeof (MessageBoxCommand),
        new FrameworkPropertyMetadata(null)
        );


    public static readonly DependencyProperty OKCommandProperty = DependencyProperty.Register(
        "OKCommand",
        typeof (ICommand),
        typeof (MessageBoxCommand),
        new FrameworkPropertyMetadata(null)
        );


    public static readonly DependencyProperty CancelCommandProperty = DependencyProperty.Register(
        "CancelCommand",
        typeof (ICommand),
        typeof (MessageBoxCommand),
        new FrameworkPropertyMetadata(null)
        );


    public static readonly DependencyProperty NoCommandProperty = DependencyProperty.Register(
        "NoCommand",
        typeof (ICommand),
        typeof (MessageBoxCommand),
        new FrameworkPropertyMetadata(null)
        );


    public static readonly DependencyProperty MessageProperty = DependencyProperty.Register(
        "Message",
        typeof (string),
        typeof (MessageBoxCommand),
        new FrameworkPropertyMetadata("")
        );

    public static readonly DependencyProperty MessageBoxButtonsProperty = DependencyProperty.Register(
        "MessageBoxButtons",
        typeof(MessageBoxButton),
        typeof(MessageBoxCommand),
        new FrameworkPropertyMetadata(MessageBoxButton.OKCancel)
        );

    public ICommand YesCommand
    {
        get { return (ICommand) GetValue(YesCommandProperty); }
        set { SetValue(YesCommandProperty, value); }
    }

    public ICommand OKCommand
    {
        get { return (ICommand) GetValue(OKCommandProperty); }
        set { SetValue(OKCommandProperty, value); }
    }

    public ICommand CancelCommand
    {
        get { return (ICommand) GetValue(CancelCommandProperty); }
        set { SetValue(CancelCommandProperty, value); }
    }

    public ICommand NoCommand
    {
        get { return (ICommand) GetValue(NoCommandProperty); }
        set { SetValue(NoCommandProperty, value); }
    }

    public MessageBoxButton MessageBoxButtons
    {
        get { return (MessageBoxButton)GetValue(MessageBoxButtonsProperty); }
        set { SetValue(MessageBoxButtonsProperty, value); }
    }

    public string Message
    {
        get { return (string) GetValue(MessageProperty); }
        set { SetValue(MessageProperty, value); }
    }

    public void Execute(object parameter)
    {
        var messageBoxResult = MessageBox.Show(Message);
        switch (messageBoxResult)
        {
            case MessageBoxResult.OK:
                OKCommand.Execute(null);
                break;
            case MessageBoxResult.Yes:
                YesCommand.Execute(null);
                break;
            case MessageBoxResult.No:
                NoCommand.Execute(null);
                break;
            case MessageBoxResult.Cancel:
                if (CancelCommand != null) CancelCommand.Execute(null); //Cancel usually means do nothing ,so can be null
                break;

        }
    }

    public bool CanExecute(object parameter)
    {
        return true;
    }

    public event EventHandler CanExecuteChanged;


    protected override Freezable CreateInstanceCore()
    {
        throw new NotImplementedException();
    }
}

最简单的方法:使用HanumanInstitute。MvvmDialogs图书馆

如果您遵循文档，您可以像这样漂亮地使用它，并与UI完全解耦

var presetName = await dialogService.ShowSavePresetViewAsync(this);