c# - 如何在 Windows Phone 中使用 MVVM Light DialogMessage

Question

我正在尝试使用 Windows Phone 7 获取 DialogMessage，但我只能找到似乎对我不起作用的 sliverlight 示例。

我将此代码放在 ViewModel 的构造函数中

主页.xaml

<phone:PhoneApplicationPage x:Class="DialogMessageMvvM.MainPage"
                            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                            xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
                            xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
                            xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                            xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                            xmlns:ignore="http://www.ignore.com"
                            mc:Ignorable="d ignore"
                            FontFamily="{StaticResource PhoneFontFamilyNormal}"
                            FontSize="{StaticResource PhoneFontSizeNormal}"
                            Foreground="{StaticResource PhoneForegroundBrush}"
                            SupportedOrientations="Portrait"
                            Orientation="Portrait"
                            d:DesignWidth="480"
                            d:DesignHeight="768"
                            shell:SystemTray.IsVisible="True"
                            DataContext="{Binding Main, Source={StaticResource Locator}}">

    <!--LayoutRoot contains the root grid where all other page content is placed-->
    <Grid x:Name="LayoutRoot"
          Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel"
                    Grid.Row="0"
                    Margin="24,24,0,12">
            <TextBlock x:Name="ApplicationTitle"
                       Text="{Binding ApplicationTitle}"
                       Style="{StaticResource PhoneTextNormalStyle}" />
            <TextBlock x:Name="PageTitle"
                       Text="{Binding PageName}"
                       Margin="-3,-8,0,0"
                       Style="{StaticResource PhoneTextTitle1Style}" />
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentGrid"
              Grid.Row="1">

            <TextBlock Text="{Binding WelcomeTitle}"
                       Style="{StaticResource PhoneTextNormalStyle}"
                       HorizontalAlignment="Center"
                       VerticalAlignment="Center"
                       FontSize="40" 
                       TextWrapping="Wrap" 
                       TextAlignment="Center" />

        </Grid>
    </Grid>

    <!-- Sample code showing usage of ApplicationBar
    <phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
            <shell:ApplicationBarIconButton x:Name="appbar_button1" IconUri="/Images/appbar_button1.png" Text="Button 1"></shell:ApplicationBarIconButton>
            <shell:ApplicationBarIconButton x:Name="appbar_button2" IconUri="/Images/appbar_button2.png" Text="Button 2"></shell:ApplicationBarIconButton>
            <shell:ApplicationBar.MenuItems>
                <shell:ApplicationBarMenuItem x:Name="menuItem1" Text="MenuItem 1"></shell:ApplicationBarMenuItem>
                <shell:ApplicationBarMenuItem x:Name="menuItem2" Text="MenuItem 2"></shell:ApplicationBarMenuItem>
            </shell:ApplicationBar.MenuItems>
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>
    -->


</phone:PhoneApplicationPage>

MainPage.xaml.cs

public partial class MainPage : PhoneApplicationPage
{
    // Constructor
    public MainPage()
    {

        InitializeComponent();

        Messenger.Default.Register<DialogMessage>(
       this,
       msg =>
       {
           var result = MessageBox.Show(
               msg.Content,
               msg.Caption,
               msg.Button);

           // Send callback
           msg.ProcessCallback(result);
       });

    }
}

主视图模型

public class MainViewModel : ViewModelBase
    {
        private const string Login = "abcd1234";

        public RelayCommand<string> CheckLoginCommand
        {
            get;
            private set;
        }

        /// <summary>
        /// The <see cref="Message" /> property's name.
        /// </summary>
        public const string MessagePropertyName = "Message";

        private string _message = "Login";

        /// <summary>
        /// Gets the Message property.
        /// Changes to that property's value raise the PropertyChanged event. 
        /// </summary>
        public string Message
        {
            get
            {
                return _message;
            }

            set
            {
                if (_message == value)
                {
                    return;
                }

                _message = value;
                RaisePropertyChanged(MessagePropertyName);
            }
        }

        /// <summary>
        /// Initializes a new instance of the MainViewModel class.
        /// </summary>
        public MainViewModel()
        {
            CheckLoginCommand = new RelayCommand<string>(CheckLogin);
        }

        private void CheckLogin(string text)
        {
            if (text == Login)
            {
                var message = new DialogMessage("Login confirmed, do you want to continue", DialogMessageCallback)
                {
                    Button = MessageBoxButton.OKCancel,
                    Caption = "Continue?"
                };

                Messenger.Default.Send(message);
            }
        }

        private void DialogMessageCallback(MessageBoxResult result)
        {
            if (result == MessageBoxResult.OK)
            {
                Message = "Continue";
            }
            else
            {
                Message = "Stop";
            }
        }
    }

Answer 1

您尚未显示创建视图模型的时间，但我猜它是在您注册侦听器之前。