如何将命令绑定到它上面的 class？

Question

大家好。

首先，我正在使用 MVVM 模式，但遇到以下问题。我有一个 Main UserControl，其中有一个 ContentControl 和一个按钮。此按钮更改 ContentControl“LoadSecondVMCommand”的内容。在随后加载的 UserControl（第二个 UserControl）中有一个后退按钮，然后应该访问命令 LoadFirstVMCommand，再次加载 FirstViewModel。所以我必须能够以某种方式从第二个用户控件访问 MainUserControl class 中的 LoadFirstVMCommand。我如何进行绑定或如何解决它，我可以从第二个 UserControl 更改 ContentControlView。

//Main UserControl

<UserControl>
    <Grid>
        <Button Command="{Binding LoadSecondVMVMCommand}">Load</Button>
        <ContentControl Content="{Binding ContentControlView}"/>
    </Grid>
</UserControl>

namespace ViewModels
{
    public class MainUserControl : ObservableObject
    {
        private object _contentControlView;
        public object ContentControlView
        {
            get { return _devicesView; }
            set { OnPropertyChanged(ref _devicesView, value); }
        }

        public ICommand LoadFirstVMCommand { get; private set; }
        public ICommand LoadSecondVMCommand { get; private set; }

        public DeviceViewModel()
        {
            LoadFirstVMCommand = new RelayCommand(LoadFirstVM);
            LoadSecondVMCommand = new RelayCommand(LoadSecondVM);
            ContentControlView = new FirstViewModel();
        }

        private void LoadFirstVM()
        {
            ContentControlView = new FirstViewModel();
        }

        private void LoadSecondVM()
        { 
            ContentControlView = new SecondViewModel();
        }
    }
}

//Second UserControl

<UserControl>
    <Grid>
        <Button>Back</Button> //this button should access the Command LoadFirstVMCommand in class MainUserControl to LoadFirstVM
    </Grid>
</UserControl>

Answer 1

private void LoadSecondVM()
{
    ContentControlView = new SecondViewModel(LoadFirstVMCommand);
}
    ...

SecondViewModel 的构造函数：

public SecondViewModel(ICommand backCommand)
{
    this.BackCommand = backCommand;
}

如何将命令绑定到它上面的 class？

How do I bind a command to a class above it?

c#

wpf

binding

mvvm