WPF MVVM 从同一层次结构级别在视图之间导航

Question

我正在尝试制作一个小程序，主要是为了学习MVVM。它是一个小型图书图书馆。

我有 4 个视图(和 4 个视图模型)。 MainWindow 是父视图，我在内容控件中显示其他 3 个视图。

其他 3 个子视图是 HomeView、BookManagementagingView、ReaderManagementagingView。

在HomeView中，我显示2个ListView(一个带有读者，一个带有书籍)，在其他2个视图中，我编辑/添加书籍或阅读器。

在我的主页视图中，我也有 2 个按钮。当我单击按钮时，我想从主视图切换到BookManagementagingView或ReaderManagementView。

如果我尝试从主窗口切换到任何视图，它可以工作。

我正在尝试做的是从HomeView切换到BookManagementagingView或ReaderManagingView。我怎样才能做到这一点？

主窗口：

<Grid>
<ContentControl Content="{Binding CurrentView}" Height="340" Width="500" />
<Button x:Name="btnHomeView" Content="Home" Command="{Binding ChangeViewToHomeView, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Margin="16,70,0,0" VerticalAlignment="Top" Width="75"/>
<Button x:Name="btnBookManagingView" Content="Reader Options" Command="{Binding ChangeViewToReaderManagView,UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Margin="96,70,0,0" VerticalAlignment="Top" Width="92"/>
<Button x:Name="btnReaderManagingView" Content="Books Options" Command="{Binding ChangeViewToBookManagView,UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Margin="193,70,0,0" VerticalAlignment="Top" Width="92"/>
</Grid>

主窗口虚拟机：

public class MainWindowViewModel : ViewModelBase
{
private object currentView;
private HomeViewModel homeVM;
private ReaderManagingViewModel readerManagingVM;
private BookManagingViewModel bookManagingVM;

public MainWindowViewModel()
{
homeVM = new HomeViewModel();
readerManagingVM = new ReaderManagingViewModel();
bookManagingVM = new BookManagingViewModel();
CurrentView = homeVM;
ChangeViewToHomeView = new DefCommand(DisplayHomeView);
ChangeViewToReaderManagView = new DefCommand(DisplayReaderManagingView);
ChangeViewToBookManagView = new DefCommand(DisplayBookManagingView);
}
public DefCommand ChangeViewToHomeView { get; private  set; }
public DefCommand ChangeViewToReaderManagView { get; private set; }
public DefCommand ChangeViewToBookManagView { get; private set; }

public object CurrentView
{
get { return currentView; }
set { currentView = value; RaisePropertyChanged(); }
}
public void DisplayHomeView()
{
CurrentView = homeVM;
}
public void DisplayReaderManagingView()
{
CurrentView = readerManagingVM;
}
public void DisplayBookManagingView()
{
CurrentView = bookManagingVM;
}

首页视图：

<Grid>
<ListView x:Name="listviewReaders" ItemsSource="{Binding ReadersList}" SelectedItem="{Binding SelectedReader, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="160" Margin="25,23,315,40">

。

<ListView x:Name="listviewBooks" ItemsSource="{Binding BookList, Mode=OneWay}" SelectedItem="{Binding SelectedBook, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="160" Margin="316,50,24,117">

。

<Button x:Name="btnEditReader" Command="{Binding EditReaderSwitch, UpdateSourceTrigger=PropertyChanged}" Content="EditR" HorizontalAlignment="Left" Margin="316,305,0,0" VerticalAlignment="Top" Width="74"/>
<Button x:Name="btnEditBook" Command="{Binding EditBookSwitch, UpdateSourceTrigger=PropertyChanged}" Content="EditB" HorizontalAlignment="Left" Margin="402,305,0,0" VerticalAlignment="Top" Width="74"/>
</Grid>

首页虚拟机：

private Reader selectedReader;
private Book selectedBook;
private BookListFilter selectedFilter;
private ObservableCollection<Book> bookList;
private ObservableCollection<Reader> readerList;
private IEnumerable<BookListFilter> bookLstItemSrc;
public HomeViewModel()
{
SelectedReader = new Reader();
SelectedBook = new Book();
SelectedFilter = BookListFilter.AllBooks;
BookDBDataContext rdb = new BookDBDataContext();
ReadersList = new ObservableCollection<Reader>(rdb.Readers);
GetBookList();
EditReaderSwitch = new DefCommand(EditReaderInfo);
EditBookSwitch = new DefCommand(EditBookInfo);
}
public DefCommand EditReaderSwitch { get; private set; }
public DefCommand EditBookSwitch { get; private set; }
private void EditBookInfo()
{
var tmpBook = new BookManagingViewModel(this);
var tmpMwvm = new MainWindowViewModel();
tmpMwvm.DisplayBookManagingView();
}
private void EditReaderInfo()
{
var tmpReader = new ReaderManagingViewModel(this);
var tmpMwvm = new MainWindowViewModel();
tmpMwvm.DisplayReaderManagingView();
}

Book & Reader ManagementViews有一堆文本框和按钮，用于在数据库中添加、删除。

书籍和阅读器管理VM具有向/从数据库添加/删除的方法(现在它们是空的，如果我设法先解决这个问题，我将完成它们)

我尝试使用EditBook/ReaderSwitch命令和EditBook/ReaderInfo()方法从HomeView导航到Book/ReaderManagingView，但它不起作用。

我做错了什么，我应该怎么做才能解决它？

对不起，长帖子。

Answer 1

您需要设置现有MainWindowViewModel实例的CurrentView属性。现在，您正在创建该类的新实例。

您可以为HomeViewModel注入MainWindowViewModel：

private readonly MainWindowViewModel _x;
public HomeViewModel(MainWindowViewModel x)
{
_x = x;
SelectedReader = new Reader();
...
}
private void EditBookInfo()
{
_x.DisplayBookManagingView();
}

主窗口视图模型：

public MainWindowViewModel()
{
homeVM = new HomeViewModel(this);
}