将数据绑定到 WPF (MVVM) 中的子视图

我正在尝试使用 WPF 和 MVVM 协议构建一个应用程序。应用程序有一个窗口和多个视图(用户控件(。其中一个视图内部还具有子视图以显示不同的数据。

我的问题我不明白如何将数据绑定到子视图。我试图了解数据是如何绑定的，但只能将数据绑定到一级。

法典

下面是一些代码。我希望它能更容易理解我的问题。

应用xaml.cs

public partial class App : Application
{
    private Engine _engine;
    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);
        MainWindow window = new MainWindow();
        _engine = new Engine("test");
        var viewModel = new MainWindowViewModel(_engine);
        EventHandler handler = null;
        handler = delegate
        {
            viewModel.RequestClose -= handler;
            window.Close();
        };
        viewModel.RequestClose += handler;
        window.DataContext = viewModel;
        window.Show();
    }
}

在这里，我创建了引擎对象并将其传递给 MainWindowViewModel，我想进一步绑定视图层次结构。

MainWindow.xaml

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:"
    xmlns:ViewModels="clr-namespace:ViewModels" 
    xmlns:View="clr-namespace:Views"
    x:Class="MainWindow" 
    Title="title" Height="800" Width="1200"
    WindowStartupLocation="CenterScreen"   Icon="Resources/Images/logo.png"
>
<DockPanel Margin="0" Background="#FF4F4F4F" LastChildFill="True">
    <Menu DockPanel.Dock="Top" Height="20">
        <MenuItem Header="File">
            <MenuItem Header="Exit"/>
        </MenuItem>
    </Menu>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*" MinWidth="200" MaxWidth="200"/>
            <ColumnDefinition Width="5*"/>
        </Grid.ColumnDefinitions>
        <View:TabView Grid.Column="0"/>
        <View:WorkspaceView Grid.Column="1"/>
    </Grid>
</DockPanel>

WorkspaceView.xaml

<UserControl x:Class="Views.WorkspaceView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:Views"
         xmlns:ViewModels="clr-namespace:ViewModels" 
         mc:Ignorable="d" 
         d:DesignHeight="750"
         d:DesignWidth="1000"             
         d:DataContext="{d:DesignInstance ViewModels:WorkspaceViewModel}"
         >
<Grid>
    <Label x:Name="label" Height="750" VerticalAlignment="Top" FontSize="60" Foreground="White" Content="{Binding Engine.BarCode}"/>
    <Grid Margin="40">
        <Grid.Background>
            <ImageBrush ImageSource="/;component/Resources/Images/logo.png" Stretch="Uniform"/>
        </Grid.Background>
        <ContentPresenter Content="{Binding CurrentView}"/>
    </Grid>
    <DockPanel>
        <!--ContentPresenter Content="{Binding CurrentView}"/-->
    </DockPanel>
</Grid>

在这里，我尝试绑定有效的{Binding Engine.BarCode}并给我一个包含正确数据的字符串。但是<ContentPresenter Content="{Binding CurrentView}"/>不会显示我在工作区视图的视图模型中设置的当前视图。

工作区视图模型.cs

    public WorkspaceViewModel()
    {
        _currentView = new InjectorView();
    }        
    public UserControl CurrentView
    {
        get { return _currentView; }
    }

• 更新：_currentView = new InjectorView();仅用于测试，当前视图应根据另一个视图中按下的按钮而变化。

WorkspaceView.xaml.cs

    public WorkspaceView()
    {
        InitializeComponent();
        this.DataContext = new WorkspaceViewModel();
    }

InjectorView.xaml

<UserControl x:Class="Views.InjectorView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:Views"
         xmlns:ViewModels="clr-namespace:ViewModels" 
         mc:Ignorable="d" 
         d:DesignHeight="750"
         d:DesignWidth="1000"
         d:DataContext="{d:DesignInstance ViewModels:InjectorViewModel}"
         >
<Grid Background="#FFAEAEAE">
    <Label x:Name="label1" Content="{Binding Engine.BarCode}"/>
</Grid>
</UserControl>

但是，如果我从 WorkspaceView.xaml 中删除d:DataContext="{d:DesignInstance ViewModels:WorkspaceViewModel}"并将this.DataContext = new WorkspaceViewModel();添加到 xaml 代码的 c# 文件中，它将显示当前视图 (InjectorView(。现在唯一的问题是当我尝试在 InjectorView 中绑定一些数据时{Binding Engine.BarCode}它不会显示与以前相同的字符串(我想它不再是对象的相同实例了？？

我错过了什么？我是否完全错误地解释了 MVVM 和 wpf？

(

由于产品的原因，我不得不删除一些代码(例如命名空间(

<View:InjectorView>
    <View:InjectorView.DataContext>
        <ViewModel:InjectorViewModel />
    <View:InjectorView.DataContext>
</View:InjectorView>

private ViewModelBase _myCurrentView;
public ViewModelBase MyCurrentView
{
    get { return _currentView; }
    set
    {
        if (value != _myCurrentView)
        {
            _myCurrentView = value;
            RaisePropertyChanged(); // You need to implement INotifyPropertyChanged interface
        }
    }
}

<ContentControl Content="{Binding MyCurrentView}">
    <ContentControl.Resources>
        <DataTemplate DataType="{x:Type ViewModels:InjectorViewModel}">
            <local:InjectorView />
        </DataTemplate>
        <DataTemplate DataType="{x:Type ViewModels:MySecondViewModel}">
            <local:MySecondView />
        </DataTemplate>
        .....
        ....
    </ContentControl.Resources>
</ContentControl>

<View:InjectorView>
    <View:InjectorView.DataContext>
        <Binding Source="{x:Static ViewModel:InjectorViewModel.Instance}" />
    <View:InjectorView.DataContext>
</View:InjectorView>