Question

最初我想传递一个“ObservableCollection＆lt; customClass＆gt;”在两个虚拟机之间，但即使是简单的消息也不适用于我。

MainViewModel

 private void openNewSpecialCustomer()
    {
        GalaSoft.MvvmLight.Messaging.Messenger.Default.Send("Musaab");
        Console.WriteLine("send done");
        AddNewSpecialCustomer a = new AddNewSpecialCustomer();
        _dialogService.showDialoge(a);
    }

AddNewSpecialCustomerViewModel

public AddNewSpecialCustomerViewModel()
    {
        GalaSoft.MvvmLight.Messaging.Messenger.Default.Register<string>(this,  doSomething);
        Console.WriteLine("Should now Receive");
        validProperties = new Dictionary<string, bool>();
        validProperties.Add("specialCustomerName",false);
        validProperties.Add("tel", false);
        allPropertiesValid = false;

    }

    public void doSomething(string s)
    {
        Console.WriteLine("Should be received");
        specialCustomerName = s;
        Console.WriteLine("s value " + s);
    }

    public String specialCustomerName
    {
        get { return _specialCustomerName; }
        set
        {
            if (_specialCustomerName != value)
            {
                _specialCustomerName = value;
               OnPropertyChanged("specialCustomerName");

            }
        }
    }

现在XAML for AddNewSpecialCustomer

<Window FlowDirection="RightToLeft" x:Class="GlassStore.AddNewSpecialCustomer"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:local="clr-namespace:GlassStore.ViewModels"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="AddNewSpecialCustomer" Height="318" Width="458">

<Window.DataContext>
    <local:AddNewSpecialCustomerViewModel/>
</Window.DataContext>
<Grid Background="{DynamicResource NormalBrush}">
    <Button Command="{Binding Save}" Content="موافق" Height="29" HorizontalAlignment="Left" Margin="31,218,0,0" Name="button1" VerticalAlignment="Top" Width="75" />
    <Label Content="إسم العميل" Height="27" HorizontalAlignment="Left" Margin="12,12,0,0" Name="label1" VerticalAlignment="Top" Width="120" />
    <TextBox Text="{Binding specialCustomerName,Mode=TwoWay,ValidatesOnDataErrors=True,ValidatesOnExceptions=True,UpdateSourceTrigger=PropertyChanged}" Height="27" HorizontalAlignment="Left" Margin="155,12,0,0" Name="textBox1" VerticalAlignment="Top" Width="210" />
    <Label Content="المنطقة/المكان" Height="27" HorizontalAlignment="Left" Margin="12,67,0,0" Name="label2" VerticalAlignment="Top" Width="120" />
    <TextBox Text="{Binding region}" Height="27" HorizontalAlignment="Left" Margin="155,67,0,0" Name="textBox2" VerticalAlignment="Top" Width="210" />
    <TextBox Text="{Binding tel,ValidatesOnDataErrors=True,ValidatesOnExceptions=True,UpdateSourceTrigger=PropertyChanged}" Height="27" HorizontalAlignment="Left" Margin="155,119,0,0" Name="textBox3" VerticalAlignment="Top" Width="210" />
    <Label Content="رقم الهاتف " Height="27" HorizontalAlignment="Left" Margin="12,119,0,0" Name="label3" VerticalAlignment="Top" Width="120" />
    <Button Content="إلغاء" Height="29" HorizontalAlignment="Left" Margin="143,218,0,0" Name="button2" VerticalAlignment="Top" Width="75" />
    <Label Content="" Height="29" HorizontalAlignment="Left" Margin="12,177,0,0" Name="label4" VerticalAlignment="Top" Width="412" />
</Grid>

你可以看到有textBox，Text属性被绑定到specialCustomerName属性，我试图通过messenger改变它，数据绑定模式是TwoWay，所以我希望我的textBox上有我的名字它加载时，（我通过信使发送我的名字）但事实并非如此，我希望这可能是更清晰的代码

提前致谢

Answer 1

你的第二个窗口构造函数是在第一个之后调用的吗？您应该首先注册，然后才发送消息。以前发送的消息未收到。很抱歉被C.O.但这种错误很可能：）

Answer 2

由于发送消息和接收消息都发生在构造函数中，因此可能导致竞争条件。注册在构造函数中接收消息，但稍后发送消息，例如在加载或命令处理程序中。

修改：

无法重现行为，以下是我用来测试此代码的代码：

<强> ViewLocator ：

public class ViewModelLocator { private static MainViewModel _main; public ViewModelLocator() { CreateMain(); } public static MainViewModel MainStatic { get { if (_main == null) { CreateMain(); } return _main; } } [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification = "This non-static member is needed for data binding purposes.")] public MainViewModel Main { get { return MainStatic; } } public static void ClearMain() { if (_main != null) { _main.Cleanup(); _main = null; } } public static void CreateMain() { if (_main == null) { _main = new MainViewModel(); } } #region [SecondViewModel] private static SecondViewModel _secondViewModel; public static SecondViewModel SecondViewModelStatic { get { if (_secondViewModel == null) { CreateSecondViewModel(); } return _secondViewModel; } } [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification = "This non-static member is needed for data binding purposes.")] public SecondViewModel SecondViewModel { get { return SecondViewModelStatic; } } public static void ClearSecondViewModel() { if (_secondViewModel != null) { _secondViewModel.Cleanup(); _secondViewModel = null; } } public static void CreateSecondViewModel() { if (_secondViewModel == null) { _secondViewModel = new SecondViewModel(); } } #endregion public static void Cleanup() { ClearMain(); ClearSecondViewModel(); } }

<强> MainViewModel

public class MainViewModel : ViewModelBase { public MainViewModel() { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { // Code runs "for real" } Messenger.Default.Send("Initializer - does not show becaus of race condition!"); } public string Welcome { get { return "Welcome to MVVM Light"; } } #region [TestCommand] private RelayCommand _cmdTest; public RelayCommand TestCommand { get { return _cmdTest ?? ( _cmdTest = new RelayCommand( () => { // Execute delegate Messenger.Default.Send("Hello!"); } ) ); } } #endregion public override void Cleanup() { // Clean up if needed base.Cleanup(); } }

<强> SecondViewModel

public SecondViewModel() { Messenger.Default.Register<string>(this, (s) => this.DoSomething(s)); if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { // Code runs "for real": Connect to service, etc... } } #region [Message] public const string MessagePropertyName = "Message"; private string _message = default(string); public string Message { get { return _message; } set { if (_message == value) { return; } _message = value; RaisePropertyChanged(MessagePropertyName); } } #endregion public void DoSomething(string s) { this.Message = s; } public override void Cleanup() { base.Cleanup(); } }

MainWindow XAML

<Window x:Class="MvvmLightTests.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="300" Width="300" DataContext="{Binding Main, Source={StaticResource Locator}}"> <Window.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Skins/MainSkin.xaml" /> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Window.Resources> <Grid x:Name="LayoutRoot"> <StackPanel> <StackPanel> <TextBlock FontSize="36" FontWeight="Bold" Foreground="Purple" Text="{Binding Welcome}" VerticalAlignment="Center" HorizontalAlignment="Center" TextWrapping="Wrap" /> <Button Content="click to send message" Margin="0,40,0,0" Command="{Binding TestCommand}" /> </StackPanel> <StackPanel DataContext="{Binding SecondViewModel, Source={StaticResource Locator}}" Margin="0,40,0,0"> <TextBlock Text="{Binding Message, TargetNullValue='--'}" FontWeight="Bold" HorizontalAlignment="Center"/> </StackPanel> </StackPanel> </Grid> </Window>

使用MVVM-Light的消息传递问题

2 个答案: