Question

我正在尝试制作一个小程序，主要是为了学习MVVM。它是一个小型图书馆。

我有4个视图（和4个视图模型）。 MainWindow是父视图，其中我在内容控件中显示另外3个视图。

其他3个子视图是HomeView，BookManagingView，ReaderManagingView。

在HomeView中，我显示2个ListViews（一个有读者，一个有书），另外两个视图我编辑/添加书籍或读者。

在我的HomeView中我也有2个按钮。当我单击要从HomeView切换到BookManagingView或ReaderManagingView的按钮时。

如果我尝试切换到MainWindow中的任何视图，它可以正常工作。

我要做的是从HomeView切换到BookManagingView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>

MainWindowVM：

    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;
    }

HomeView：

<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>

HomeVM：

 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＆amp; Reader ManagingViews 有一堆文本框和按钮，用于添加，删除数据库或从数据库中删除。

Book＆amp; Reader ManagingVM有添加/删除数据库的方法（现在它们是空的，如果我先设法解决这个问题，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，我该怎么做才能解决它？

很抱歉这篇长篇文章。

Answer 1

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

您可以使用HomeViewModel注入MainWindowViewModel：

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

private void EditBookInfo()
{
    _x.DisplayBookManagingView();
}

<强> MainWindowViewModel：

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

WPF MVVM导航来自同一层级

1 个答案: