以编程方式更改 Content ViewModel 中的 ContentControl 内容

Question

MainWindow.xaml

<Window.Resources>
    <DataTemplate DataType="{x:Type local2:StartPageViewModel}">
        <local1:StartPage/>
    </DataTemplate>
    <DataTemplate DataType="{x:Type local2:SecondPageViewModel}">
        <local1:SecondPage/>
    </DataTemplate>
</Window.Resources>
<DockPanel>
    <StackPanel DockPanel.Dock="Left">
        <Label Content="[res][per]" />
        <Button Command="{Binding CommandStartView}">
            First
        </Button>
        <Button Command="{Binding CommandSecondView}">
            Second
        </Button>            
    </StackPanel>
    <ContentControl x:Name="Pages" DockPanel.Dock="Right" Content="{Binding SelectedViewModel}"/>
</DockPanel>

MainWindowViewModel.cs

class MainWindowViewModel : BaseViewModel
{

    private object selectedViewModel;

    public object SelectedViewModel
    {
        get { return selectedViewModel; }
        set { selectedViewModel = value; OnPropertyChanged("SelectedViewModel"); }
    }

    public ICommand CommandStartView { get; set; }
    public ICommand CommandSecondView { get; set; }

    public MainWindowViewModel()
    {

        CommandStartView = new RelayCommand(openStartView);
        CommandSecondView = new RelayCommand(openSecondView);

    }

    private void openStartView(object obj)
    {
        SelectedViewModel = new StartPageViewModel();
    }

    private void openSecondView(object obj)
    {
        SelectedViewModel = new SecondPageViewModel();
    }

}

StartPage.xaml

<StackPanel>
    <Label Content="First Page" />
    <Button Content="Second" Command="{Binding Path=DataContext.CommandSecondView, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"/>
    <Button Content="Do Something" Command="{Binding CommandDoBeforeSecondView}"/>
</StackPanel>

StartPageViewModel.cs

class StartPageViewModel : BaseViewModel
{
    public ICommand CommandDoBeforeSecondView { get; set; }

    public StartPageViewModel()
    {

        CommandDoBeforeSecondView = new RelayCommand(openSecondView);
    }

    private void openSecondView(object obj)
    {
        Console.WriteLine("DO SOME CODE");

        //Then change Content programmatically

    }
 }

问题： 如何使用 StartPage 中的第二个按钮更改 MainWindow ContentControl 中的内容？我想执行一些代码，然后更改内容。

关于第一条评论，我想我必须在我的 StartPageViewModel 中添加对 MainWindowViewModel 的引用，我该怎么做？

编辑

我的工作解决方案：

MainWindowViewModel.cs

private void openStartView(object obj)
{
    SelectedViewModel = new StartPageViewModel(this);
}

StartPageViewModel.cs

class StartPageViewModel : BaseViewModel
{
    private MainWindowViewModel mainWindow;
    public ICommand CommandDoBeforeSecondView { get; set; }

    public StartPageViewModel(MainWindowViewModel _mainWindow)
    {
        mainWindow = _mainWindow;
        CommandDoBeforeSecondView = new RelayCommand(openSecondView);
    }

    private void openSecondView(object obj)
    {
        Console.WriteLine("DO SOME CODE");
        mainWindow.SelectedViewModel = new SecondPageViewModel();

    }
}

Answer 1

我的工作解决方案：

MainWindowViewModel.cs

private void openStartView(object obj)
{
    SelectedViewModel = new StartPageViewModel(this);
}

StartPageViewModel.cs

class StartPageViewModel : BaseViewModel
{
    private MainWindowViewModel mainWindow;
    public ICommand CommandDoBeforeSecondView { get; set; }

    public StartPageViewModel(MainWindowViewModel _mainWindow)
    {
        mainWindow = _mainWindow;
        CommandDoBeforeSecondView = new RelayCommand(openSecondView);
    }

    private void openSecondView(object obj)
    {
        Console.WriteLine("DO SOME CODE");
        mainWindow.SelectedViewModel = new SecondPageViewModel();

    }
}

感谢 Peter Duniho，他回答了上面的评论：

you should just pass this when creating StartPageViewModel in the MainWindowViewModel, then the StartPageViewModel will have the reference (you'll have to add the parameter to the constructor of course)

以编程方式更改 Content ViewModel 中的 ContentControl 内容

Change ContentControl Content from Content ViewModel programmatically

c#

wpf

mvvm

contentcontrol