Wpf MEF、Prism和导航上的新视图实例

下面的代码处理视图的共享实例。现在，我试图实现的是，每次导航到

ViewB

时，我都需要一个视图的新实例及其备份视图模型。我尝试了下面的各种组合，但它们最终似乎都以

RequestNavigate

在我第二次尝试导航到ViewB时失败而告终

在视图导航到一次之后，我还尝试将

IsNaviagtionTarget

设置为false

引导程序：

public void Initialize()
{
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewA));
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewB));
}

[RegionMemberLifetime(KeepAlive = false)]
[Export]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal partial class ViewB
{
    [ImportingConstructor]
    public ViewB(ViewBViewModel viewModel)
    {
        InitializeComponent();
        DataContext = viewModel;
    }
}

[Export(typeof(ViewBViewModel))]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal class ViewBViewModel : BindableBase, INavigationAware
{
    public void OnNavigatedTo(NavigationContext navigationContext)
    {
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }

    public void OnNavigatedFrom(NavigationContext navigationContext)
    {
    }
}

public override void Execute(object parameter)
{
    _regionManager.RequestNavigate(RegionNameConstants.MainRegion, new Uri(nameof(ViewB), UriKind.Relative));
}

ViewB（类）：

public void Initialize()
{
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewA));
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewB));
}

[RegionMemberLifetime(KeepAlive = false)]
[Export]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal partial class ViewB
{
    [ImportingConstructor]
    public ViewB(ViewBViewModel viewModel)
    {
        InitializeComponent();
        DataContext = viewModel;
    }
}

[Export(typeof(ViewBViewModel))]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal class ViewBViewModel : BindableBase, INavigationAware
{
    public void OnNavigatedTo(NavigationContext navigationContext)
    {
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }

    public void OnNavigatedFrom(NavigationContext navigationContext)
    {
    }
}

public override void Execute(object parameter)
{
    _regionManager.RequestNavigate(RegionNameConstants.MainRegion, new Uri(nameof(ViewB), UriKind.Relative));
}

视图视图模型：

public void Initialize()
{
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewA));
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewB));
}

[RegionMemberLifetime(KeepAlive = false)]
[Export]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal partial class ViewB
{
    [ImportingConstructor]
    public ViewB(ViewBViewModel viewModel)
    {
        InitializeComponent();
        DataContext = viewModel;
    }
}

[Export(typeof(ViewBViewModel))]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal class ViewBViewModel : BindableBase, INavigationAware
{
    public void OnNavigatedTo(NavigationContext navigationContext)
    {
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }

    public void OnNavigatedFrom(NavigationContext navigationContext)
    {
    }
}

public override void Execute(object parameter)
{
    _regionManager.RequestNavigate(RegionNameConstants.MainRegion, new Uri(nameof(ViewB), UriKind.Relative));
}

ViewA只有一个按钮，其中包含一个命令，该命令调用：

查看导航命令：

public void Initialize()
{
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewA));
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewB));
}

[RegionMemberLifetime(KeepAlive = false)]
[Export]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal partial class ViewB
{
    [ImportingConstructor]
    public ViewB(ViewBViewModel viewModel)
    {
        InitializeComponent();
        DataContext = viewModel;
    }
}

[Export(typeof(ViewBViewModel))]
[PartCreationPolicy(CreationPolicy.NonShared)]
internal class ViewBViewModel : BindableBase, INavigationAware
{
    public void OnNavigatedTo(NavigationContext navigationContext)
    {
    }

    public bool IsNavigationTarget(NavigationContext navigationContext)
    {
        return true;
    }

    public void OnNavigatedFrom(NavigationContext navigationContext)
    {
    }
}

public override void Execute(object parameter)
{
    _regionManager.RequestNavigate(RegionNameConstants.MainRegion, new Uri(nameof(ViewB), UriKind.Relative));
}

---

不要向引导程序中的区域管理器注册

typeof（ViewB）

：

public void Initialize()
{
    _regionManager.RegisterViewWithRegion(RegionNameConstants.MainRegion, typeof(ViewA));
}

由于您正在导航到

nameof（ViewB）

的Uri，因此还应该导出合同名为

nameof（ViewB）

的视图：

然后，每次使用以下命令导航到ViewB时，都应获得一个新的ViewB实例：

_regionManager.RequestNavigate(RegionNameConstants.MainRegion, new Uri(nameof(ViewB), UriKind.Relative));

神奇之处在于（ViewB）的名称，它在没有我在回答中使用的额外寄存器的情况下工作。好电话。