关于c＃：如何在MVVM中的UserControl之间进行通信-WPF应用程序

How to communicate between UserControl in MVVM - WPF Application

我想创建一个带有左侧菜单的应用程序，该菜单将更改右侧的内容。
为此，我有一个带有两个ContentControl的MainWindow(一个将容纳一个UserControl'菜单'，另一个将容纳所选的UserControl'红色'或'绿色'。

问题是右侧的内容不会更改...

我进行了一些研究，看到了诸如依赖注入，委托，事件，消息总线，ViewModelLocator等概念。
但我不知道在这种情况下哪一个最合适，以及如何实现它。 (我不想使用MVVMLight或类似的任何插件)

事先感谢您的关注。

为此，我使用了MVVM模式和DataTemplate绑定：

应用程式

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<Application.Resources>
<DataTemplate DataType="{x:Type viewModel:MainViewModel}">
<view:MainWindow />
</DataTemplate>
<DataTemplate DataType="{x:Type viewModelMenu:LeftViewModel}">
<viewMenu:Left />
</DataTemplate>
<DataTemplate DataType="{x:Type viewModelContent:RedViewModel}">
<viewContent:Red />
</DataTemplate>
</Application.Resources>

ViewModel.cs

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public abstract class ViewModel : INotifyPropertyChanged
{
#region Properties

private ViewModel _mainContent;

public ViewModel MainContent
{
get => _mainContent;
set
{
_mainContent = value;
OnPropertyChanged();
MessageBox.Show(nameof(MainContent));
}
}

#endregion Properties

public ViewModel()
{
InitCommands();
}

protected abstract void InitCommands();

#region Factory Method - CreateCommand

protected ICommand CreateCommand(Action execute, Func<bool> canExecute)
{
return new RelayCommand(
execute: execute,
canExecute: canExecute
);
}

protected ICommand CreateCommand< T >(Action< T > execute, Predicate< T > canExecute)
{
return new RelayCommand< T >(
execute: execute,
canExecute: canExecute
);
}

#endregion Factory Method - CreateCommand

public event PropertyChangedEventHandler PropertyChanged;

protected virtual void OnPropertyChanged([CallerMemberName] string propertyName ="")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}

MainViewModel.cs

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internal class MainViewModel : ViewModel
{
private ViewModel _leftMenu;
public ViewModel LeftMenu
{
get => _leftMenu;
set
{
_leftMenu = value;
OnPropertyChanged();
}
}

public MainViewModel()
{
LeftMenu = new LeftViewModel();
}

protected override void InitCommands()
{
}

LeftViewModel.cs

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internal class LeftViewModel : ViewModel
{
public ICommand ChangeContentToRed { get; set; }
public ICommand ChangeContentToGreen { get; set; }

protected override void InitCommands()
{
ChangeContentToRed = new RelayCommand(
execute: () => MainContent = new RedViewModel(),
canExecute: () => !(MainContent is RedViewModel)
);

ChangeContentToGreen = new RelayCommand(
execute: () => MainContent = new GreenViewModel(),
canExecute: () => !(MainContent is GreenViewModel)
);
}
}

RedViewModel和GreenViewModel为空，所以我不显示代码而是扩展ViewModel

Window.xaml

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<Window.DataContext>
<viewModel:MainViewModel />
</Window.DataContext>

<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="3*" />
</Grid.ColumnDefinitions>

<ContentControl Grid.Column="0" Content="{Binding Path=LeftMenu}" />
<ContentControl Grid.Column="1" Content="{Binding Path=MainContent}" />
</Grid>

Left.xaml

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<UserControl.DataContext>
<viewModel:LeftViewModel />
</UserControl.DataContext>

<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Button
Grid.Row="0"
Command="{Binding Path=ChangeContentToRed}"
Content="Red" />
<Button
Grid.Row="1"
Command="{Binding Path=ChangeContentToGreen}"
Content="Green" />
</Grid>

红色和绿色只是两个带有红色和绿色网格的UserControl